PORTABLE HYBRID HYDRONIC HEATING SYSTEM

This application claims priority to Canadian Application No. 3,199,210 filed on May 8, 2023, the disclosure of which is hereby incorporated by reference.

The present invention relates to a hybrid hydronic heating system that employs a primary heater powered with fuel and a second additional electric heater.

BACKGROUND

Hydronic heaters use liquids or gases as a heat transfer medium in heating systems. The heat transfer medium is heated by a heater and then this heated transfer medium is used to transfer this heat to another location. While many hydronic heating systems are permanently installed in a location, portable hydronic heating systems are used, especially in construction projects or when used to provide temporary heat while maintenance of permanent equipment takes place, to be moved to a site where heating is temporarily required. One typical application of these portable hydronic heaters is as part of a ground thaw system where fluid circulation lines are run along a ground surface to be thawed. A heater will heat a liquid, such as glycol, and then circulate this heated liquid through the fluid circulation lines running along the ground surface, to heat up and thaw the frozen ground surface (typically with insulating blankets laid over the circulation lines to reduce the amount of heat released into the air instead of transferred into the ground). These portable hydronic systems can also be used in other applications, such as preventing frost, providing heat in subzero environments, curing concrete, heating insulated construction sites, heating large water tanks, drying water damaged buildings, etc.

Because these portable hydronic systems are contemplated to be used at various work sites and other, often remote, locations, the heaters used in these systems are usually powered with fuel and specifically fossil fuels because of the lack of adequate electrical power at some of the sites. Even where there is a good source of electrical power at a site, the significant energy required to supply the required heat for an application, especially at the early stages of heating, is often more than an electrical supply alone can provide.

While the use of fossil fuels as a power source for the heaters provides the advantages of allowing the system to be used on various work sites or other locations and being able to supply the energy needed for the heating application, the burning of fossil fuels releases harmful emissions, harming the environment, and the fuel can be significantly more costly than electricity.

SUMMARY OF THE INVENTION

In a first aspect, a portable fluid heating system is provided. The system can include a primary heater using a fuel to heat a transfer fluid, a circulating pump for pressurizing the transfer fluid that has been heated by the primary heater, to circulate the transfer fluid through the system, a heat accessory which the transfer fluid can be circulated through, and an electric heater for heating the transfer fluid.

In a further aspect, the system can include a first manifold and a second manifold and wherein the plurality of fluid circulation lines run between the first manifold and the second manifold.

In a further aspect, the system can include a flow reverser connected between the primary heater and the first distribution manifold and the second distribution manifold, the flow reverser operative to reverse the flow of heat transfer fluid through the flow reverser.

In a further aspect, the system can include a flow rectifier to direct a flow of heat transfer fluid through the electric heater in a single direction.

In another aspect, a method for circulating heated fluid is provided. The method can include heating a heat transfer fluid with a primary heater using a fuel, circulating the heated heat transfer fluid through a heat accessory, and, further heating the heat transfer fluid with an electric heater.

DESCRIPTION OF THE DRAWINGS

A preferred embodiment of the present invention is described below with reference to the accompanying drawings, in which:

FIG. 1 is a schematic illustration of a portable circulating fluid system having a primary heater and an electric heater;

FIG. 2 is a schematic illustration of a portable circulating fluid system having a primary heater, an electric heater, and a flow reverser to selective change the direction of flow;

FIG. 3 is a schematic illustration of a portable circulating fluid system having a primary heater, an electric heater, a flow reverser, a flow switch and a flow rectifier showing the fluid flowing in a first direction; and

FIG. 4 is a schematic illustration of the portable circulating fluid system of FIG. 3 showing fluid flowing in a second direction.

DETAILED DESCRIPTION OF THE ILLUSTRATED EMBODIMENTS

FIG. 1 illustrates a portable circulating fluid system 10 for increasing the temperature of a material 2. The circulating fluid system 10 can heat a heat transfer fluid and then circulate the heated heat transfer fluid through a heat accessory 60, such as a series of fluid circulation lines 62. By placing the heat accessory 60 against or proximate the material 2, heat transferred from the heated heat transfer fluid by the heat accessory 60 can warm the material 2. The material 2 can be frozen ground, concrete, etc. The system 10 can be used to heat cold ground, thaw frozen ground, prevent frost, provide heat in subzero environments, cure concrete, etc. if the heat accessory 60 is a plurality of fluid circulation lines 62 or heat insulated construction sites, heat large water tanks, dry water damaged buildings, etc. if the heat accessory 60 is some other hydronic heating device.

The circulating fluid system 10 can include: a primary heater 20; a circulating pump 30; a first distribution manifold 40; a second distribution manifold 50; one or more heat accessories 60; and, an electric heater 80.

The primary heater 20 uses a fuel to supply energy and can comprise a gas-fired and/or an oil-fired fluid heater, such as a water heater, capable of increasing the temperature of a heat transfer fluid. If the primary heater 20 is a gas-fired heater, the fuel can be a gas such as propane, natural gas, etc. If the primary heater 20 is an oil-fired heater, the fuel can be diesel, light oil, etc. In some aspects, the primary heater 20 can be alternately operated as a gas-fired or an oil-fired heater.

The primary heater 20 can also include one or more heat exchangers and other components to transfer heat to the heat transfer fluid.

The primary heater 20 can have a supply port 22 where heat transfer fluid that has been heated by the primary heater 20 can exit the primary heater 20 and a return port 24 where heat transfer fluid can be returned to the primary heater 20.

The circulating pump 30 can work in conjunction with the primary heater 20, with the circulating pump 30 pressurizing the heated transfer fluid heated by the primary heater 20 so that the heat transfer fluid will flow out of the supply port 22 and through the system 10.

In one aspect, the heat accessories 60 can be a plurality of fluid circulation lines 62 and the first distribution manifold 40 can be used to route heated heat transfer fluid supplied from the supply port 22 of the primary heater 20 through a supply conduit 26 to the first distribution manifold 40 and to the plurality of fluid circulation lines 62, with the first distribution manifold 40 splitting up a single flow of heated heat transfer fluid to a flow of heated transfer fluid through each fluid circulation line 62 connected to the first distribution manifold 40 and then the second distribution manifold 50 can be connected to the other end of the plurality of fluid circulation lines 62 to collect the various flows of heat transfer fluid that have circulated through the fluid circulation lines 62 and combine it into one flow of heat transfer fluid to be directed back to the primary heater 20.

The plurality of fluid circulation lines 62 can be flexible hoses allowing the fluid circulation lines 62 to be run over the material 2 to be heated such as in a loop or loops passing over the material 2. For example, if the system 10 is being used to thaw frozen ground, the fluid circulation lines 62 can be routed to run along the frozen ground.

Insulating blankets can be used to cover the fluid circulation lines 62 after they are run to ensure more of the heat from the heat transfer fluid is transferred to the material 2 rather than to the air above the fluid circulation lines 62.

The electric heater 80 can have a submersible electrical element to increase the temperature of heat transfer fluid passing through the electric heater 80. The electric heater 80 can have a separate power source from the power source of the primary heater 20.

In one aspect, the electric heater 80 can be provided inline with a return conduit 28 directing the cooled heat transfer fluid that has passed through the plurality of fluid circulating lines 62 from the second distribution manifold 50 back to the primary heater 20, so that the heat transfer fluid that has passed through the fluid circulation lines 62 and been cooled by the material 2, passes through the electric heater 80 before being returned to the primary heater 20. In this manner, the electric heater 80 can increase the temperature of the heat transfer fluid that has been cooled by passing through the heat accessory 60 before the heat transfer fluid is returned to the primary heater 20 through the return port 24.

By placing the electric heater 80 just upstream in the system 10 from the primary heater 20, the electric heater 80 would be placed where the heat transfer fluid is at its coldest allowing the electric heater 80 to contribute as much heat to the heat transfer fluid as it can before the heat transfer fluid passes to the primary heater 20 for further heating.

The actual flow rates and the temperatures of the heat transfer fluid as it circulates through the system will be dependent on multiple factors, such as the capacity of the primary heater 20, the size and length of the fluid circulation lines 62, heat exchange loads and flows when used with additional accessories such as fan coils, submersible heat exchangers, plate heat exchangers, etc.

In operation, heat transfer fluid supplied to the primary heater 20 will be heated and then circulated, using the circulation pump 30, through the system 10. The heated heat transfer fluid will be circulated from the supply port 22 of the primary heater 20 through the supply conduit 26 to the first distribution manifold 40. The first distribution manifold 40 will distribute the single flow of heated heat transfer fluid from the supply conduit 26 to the plurality of fluid circulation lines 62 connected to the first distribution manifold 40.

Heated heat transfer fluid can flow through each of the fluid circulation lines 62 and over the material 2, transferring heat from the heated heat transfer fluid to the material 2. This will heat the material 2 if the temperature of the material is less than the temperature of the heat transfer fluid flowing through the fluid circulation lines 62, while cooling the heat transfer fluid.

After heat transfer fluid has flowed through the length of a fluid circulation line 62 and transferred heat to the material 2, the cooled heat transfer fluid can reach the second distribution manifold 50 where the cooled heat transfer fluid can be combined with the cooled heat transfer fluid from the other fluid circulation lines 62 and routed through the return conduit 28 via the electric heater 80. The electric heater 80 can supply heat to the cooled heat transfer fluid, raising the temperature of the heat transfer fluid before the heat transfer fluid is supplied back to the primary heater 20 through the return port 24.

Heating the material 2 can require a significant amount of energy in the form of fuel (i.e. natural gas, propane, diesel, light oil, etc.) for the primary heater 20 to supply the necessary heat to the heat transfer fluid so that the heated heat transfer fluid can be circulated through the fluid circulation lines 62 to heat the material 2 to the desired temperature, especially if the system 10 is being used to thaw frozen ground or cure concrete during cold temperatures. The colder the material 2 being heated and the bigger the temperature differential between the temperature of the heated heat transfer fluid and the material 2, the greater the energy requirement will be typically, to bring the temperature of the material 2 up to the desired temperature.

In many cases, electricity alone using the electric heater 80 will not be enough to supply the heat required to bring the material 2 up to the desired temperature. Works sites typically have varying amounts of electricity available, however, it is not uncommon to have 20 KW to 30 KW of electrical energy available from a buildings electrical service at a worksite. While this may not be enough electrical energy necessary to heat the heat transfer fluid enough to heat the material 2 to the desired temperature, this electrical energy available to be supplied to the heater 80 can provide a portion of the total energy required and reduce the amount of energy required to be supplied by the primary heater 20, thereby reducing the amount of fuel used by the primary heater 20. In this manner, the total amount of fuel, typically fossil fuel, required by the primary heater 20 can be reduced and replaced with electrical energy present at the site.

The primary heater 20 will use fuel as an energy source to heat the heat transfer fluid to a desired supply temperature. However, the higher the temperature of the heat transfer fluid entering the primary heater 20, the lower the temperature differential between the desired supply temperature and the heat transfer fluid and therefore the less energy required by the primary heater 20 to increase the incoming heat transfer fluid to the desired supply temperature.

Typically, the primary heater 20 may not be able to heat the heat transfer fluid to the desired temperature as soon as the system 10 is started, but instead will have to circulate the heat transfer fluid 10 through the system 10, heating the heat transfer fluid with the primary heater 20 as it circulates, until the heat transfer fluid can be heated to the desired temperature as it passes through the primary heater 20.

In early stages of heating the material 2, the electric heater 80 may only provide a small portion of the total energy required to heat the cooled heat transfer fluid to the desired supply temperature, requiring the primary heater 20 to supply most of the energy.

For example, for a ground thaw application, approximately 400,000 BTU of energy may be required to run an average sized ground thaw unit. In the early stages, when the ground is still frozen and at its coldest, the primary heater 20 may be operating at close to its maximum output because the heat exchange between the heated heat transfer fluid in the fluid circulation lines 62 and the cold material 2 (in this case the frozen ground) is at its greatest. The electric heater 80 can be contributing the maximum amount of heat that it can to the heat transfer fluid and will be contributing some portion of the total energy required to heat the heat transfer fluid before the heat transfer fluid is returned to the primary heater 20, but the electric heater 80 may not be able to supply all of the necessary heat. However, the electric heater 80 is still contributing to the total energy required for heating the heat transfer fluid to the desired supply temperature and may be contributing 10% to 25% of the total energy required to heat the heat transfer fluid, which is not insignificant and reduces the amount of energy required to be supplied by the primary heater 20 and therefore reduces the emissions of fossil fuels used by the primary heater 20.

However, as the system 10 continues to be used to increase the temperature of the material 2 and the temperature of the material 2 increases, the temperature differential between the temperature of the heated heat transfer fluid and the material 2 becomes less, resulting in less heat being transferred between the heat transfer fluid and the material 2. This lowers heat transfer to the material 2 from the heat transfer fluid passing through the fluid circulation lines 62 and results in the heat transfer fluid not being cooled as much as when the system 10 was first started and therefore having a higher temperature when it reaches the second distribution manifold 50.

This higher temperature of the heat transfer fluid entering the electric heater 80 will allow the energy supplied by the electric heater 80 to get the temperature of the heat transfer fluid closer to the desired supply temperature, resulting in the primary heater 20 having to supply less energy to heat the heat transfer fluid to the desired supply temperature.

For example, for ground thaw applications, during the later stages of the thawing, the top layers of the ground surface (the material 2) will be warmed and the heat exchange between the heated heat transfer fluid circulating through the fluid circulation lines 62 and the material 2 will be reduced. For example, this heat transfer could be reduced as much as 50-60%, because less heat is required to be added to the heat transfer fluid to get it back up to the desired supply temperature. At this point, the electrical heater 80 can be contributing a greater portion of the heat required to heat the heat transfer fluid back up to the desired supply temperature, further reducing the amount of energy the primary heater 20 has to supply because the primary heater 20 has to heat the heat transfer fluid less. At this stage, the electric heater 80 could be contributing as much as 60% of the energy required, for example, further reducing the amount of energy the fuel using primary heater 20 has to supply.

As the temperature of the material 2 continues to increase towards the desired temperature, the heat supplied to the heat transfer fluid by the electric heater 80 can become an increasingly larger portion of the energy needed to heat the heat transfer fluid to the desired supply temperature, decreasing the portion of heat the primary heater 20 must supply to the heat transfer fluid to reach the desired supply temperature and therefore decreasing the amount of energy required to be provided by the primary heater 20.

In the early stages of heating the material 2, the electric heaters 80 set point temperature (the temperature the electric heater 80 will turn off and stop providing heat to the heat transfer fluid passing through the electric heater 80) will likely not be reached allowing the electric heater 80 to contribute the maximum amount of heat. In later stages, the increased temperature of the material 2 will reduce the cooling of the heat transfer fluid as it passes through the fluid circulation lines 62 causing the heat transfer fluid reaching the electric heater 80 to be warmer. If the temperature of the heat transfer fluid reaches the temperature set point, the electric heater 80 may cycle on and off only supplying additional heat when needed.

For example, the primary heater 20 may be set to heat the heat transfer fluid to 180° F. and return heat transfer fluid at 80° F. from the second distribution manifold 50 after transferring its heat to the material 2 as it passes through the fluid circulation lines 62. The electric heater 80 can increase the temperature of the heat transfer fluid until it has transferred its maximum amount of energy, heating the heat transfer fluid that passes through the electric heater 80 to 120° F. for example, before the heat transfer fluid passes to the primary heater 20 to be heated the rest of the way to the desired supply temperature, 180° F. The closer the electric heater 80 can heat the heat transfer fluid to 180° F., the less energy the primary heater 20 will have to provide to the heat transfer fluid. Eventually, if the electric heater 80 can heat the heat transfer fluid to 180° F. (such as if the heat transfer fluid reaching the electric heater 80 is close enough to 180° F. that the electric heater 80 can supply enough heat to heat it to this temperature), the primary heater 20 will have reached its set point (the desired supply temperature) and can automatically shut off its burner while continuing to circulate the heated heat transfer fluid through the fluid circulation lines 62 and the electric heater 80.

The use of the electric heater 80 in conjunction with the primary heater 20 can also provide critical redundancy as a secondary source of heat for an application. For example, in the application of cold weather concrete curing, the material 2 would be the poured concrete that has to cure. In this application, it is critical to maintain the curing concrete (the material 2) above freezing to prevent improper curing of the concrete, which can result in a catastrophic failure of the concrete and may require expensive repouring to correct. The electric heater 80 can provide a heat source backup, if the primary heater 20 experiences failure, with the electric heater 80 hopefully providing enough heat to the heat transfer fluid without the primary heater 20 to maintain the temperature of the material 2 or extending the time permitted to find and correct the failure by supplying some heat to slow the cooling of the material 2. The failure of the primary heater 20 can occur in the middle of the night or in remote areas so this redundancy can be critical.

In a further aspect, the electric heater 80 multi-voltage device. If the available power voltage is known, then the electric heater 80 could be configured to work at a dedicated voltage that matches the available power voltage. However, since the system 10 is a portable system meant to be taken to different job sites where varying voltages of electricity may be available, the electric heater 80 can be configurable to be operable with different voltages.

The electric heater 80 can have multiple voltage connections. In one aspect, the electric heater 80 could have both a 480V and a 240/208V flanged electrical inlet connections. The circuits could be isolated by contactors which would energize the proper element combination when connected to the appropriate voltage.

Wattage/voltage and design of resistance heaters is somewhat complex based on ohms law. For example, if you apply 480 volts to a 480V 24 KW element the energy consumed will be 24 KW. If you apply 240V to the same element the energy consumed will be 25% of the 480V design wattage (6 KW). Applying 208V (most common) would result in 4.5 KW consumption. This would effectively create a scenario where a dual voltage heater would be 480V-24 KW, 240V-6 KW, and 208V-4.5 KW. The reduction in wattage would render the 208V configuration almost ineffective. Conversely you cannot apply 480V to a 240V element without causing element failure or extreme loss of element longevity.

In an ungrounded 3 phase Wye configuration, the element array would operate at phase voltage. 480V line voltage=277V phase voltage or 240/208V line voltage=138.5/120 phase voltage. Each leg of the Wye configuration with 4 elements in series would have 277V applied across 4 elements. 277 divided by 4=69.25V.

To remedy this scenario, the electric heater 80 can have multiple 69V elements. Resistors in series can be used to allow various combinations of the multiple 69V elements, i.e. 240V, 480V and 600V which are common 3 phrase voltages providing 139V, 277V and 347V phase voltages. For example, twelve 2 KW 69V elements in a 3 phase Y configuration would see 480V applied to four 2 KW-69V elements in series per phase, giving a total of 24 KW. In a 240V application, 240V could be applied across two 69V 2 KW elements in series per phase giving a total of 12 KW. The heater rating would then be 480V-24 KW, 240V-12 KW, 208V-9 KW. A 9 KW contribution is large enough to be cost effective and relevant.

A 208/240V 3 phase voltages share many electrical components and 208V can be applied to two 69V elements in series per phase without sacrificing element longevity.

Alternatively, the electric heater 80 could be provided between the supply port 22 and the first distribution manifold 40 and inline with the supply conduit 26 to further heat heat transfer fluid exiting the primary heater 20 that has already been heated by the primary heater 20. The electric heater 80 can be set to a higher temperature than the primary heater 20. For example, if heat transfer fluid is heated to 160° F. by the primary heater 20, the electric heater 80 could heat the heat transfer fluid further to 180° F.

In certain applications where a higher supply temperature is desired for the heat transfer fluid reaching the fluid circulation lines 62, the electric heater 80 further heating the heat transfer fluid after it exits the primary heater 20 can boost the temperature of the heat transfer fluid without causing pump cavitation. Pump cavitation is common when the temperature of a 50% aqueous propylene fluid being pumped is higher than 190° F. Cavitation is caused when pump suction (negative pressure) lowers the vaporization temperatures of the liquid being pumped and gas bubbles form in the liquid. The primary heater 20 could be used to heat the heat transfer fluid to 180° F. and the electric heater 80 can be set to 200° F. to further increase the temperature of the heat transfer fluid to increase the supply temperature of the heat transfer fluid to 200° F. without causing pump cavitation in the circulating pump 30 as the higher temperature heat transfer fluid is now on the pressure side of the circulation pump 30.

FIG. 2 illustrates a circulating fluid system 110 for adjusting the temperature of a material 102 that includes a flow reverser 170 so that the flow of heat transfer fluid through fluid circulation lines 162 can be periodically reversed.

Like the circulating fluid system 10 shown in FIG. 1, the circulating fluid system 110 can include: a primary heater 120; a circulating pump 130; a plurality of fluid circulation lines 162; and an electric heater 180. In addition, the circulating fluid system 110 can further include the flow reverser 170; a first distribution manifold 140; and, a second distribution manifold 150.

The primary heater 120 uses a fuel to supply energy and is capable of increasing the temperature of a heat transfer fluid, such as glycol, supplied to the primary heater 120. The primary heater 120 can have a supply port 122 where heat transfer fluid that has been heated by the primary heater 120 can exit the primary heater 120 and a return port 124 where heat transfer fluid can be returned to the primary heater 120.

The circulating pump 130 can work in conjunction with the primary heater 120, with the circulating pump 130 pressurizing the heat transfer fluid heated by the primary heater 120 so that the heat transfer fluid will flow out of the supply port 122 and through the system 110.

The flow reverser 170 can have an intake port 172 and an outlet port 174 with the intake port 172 being connectable to the supply port 122 of the primary heater 120 by a conduit and the outlet port 174 being connectable to the return port 124 of the primary heater 120 by a conduit so that pressurized heated heat transfer fluid from the supply port 122 can be supplied to intake port 172 of the flow reverser 170 and cooled heat transfer fluid can be routed from the outlet port 174 of the flow reverser 170 to the return port 124 of the primary heater 120.

The flow reverser can also be provided with a first port 176 and a second port 178 and the flow reverser 170 can selectively alter the flow of heat transfer fluid through the flow reverser by selecting between: a first direction, operably connecting the intake port 172 of the flow reverser with the first port 176 and operably connecting the outlet port 174 of the flow reverser 170 to the second port 178; and, a second direction, operatively connecting the intake port 172 of the flow reverser 170 to the second port 178 and operatively connecting the outlet port 174 of the flow reverser 170 to the first port 176.

The first distribution manifold 140 can be connected by a conduit to the first port 176 and the second distribution manifold 150 can be connected by a conduit to the second port 178. The plurality of fluid circulation lines 162 can be connected between the first distribution manifold 140 and the second distribution manifold 150.

The electric heater 180 can be connected in parallel with the plurality of fluid circulation lines 162 by accessory ports 186, 188. A first accessory port 186 can be operably connected to the first port 176 on the flow reverser 170 and a second accessory port 188 can be operably connected to the second port 178 of the flow reverser to put the electric heater 180 in parallel to the fluid circulation lines 162 when the electric heater 180 is connected to the accessory ports 186, 188. Because the electric heater 180 will typically offer very little resistance to the flow of heat transfer fluid through the electric heater 180 compared to the resistance that would typically be created by the first distribution manifold 140, the fluid circulation lines 162 and the second distribution manifold 150, a flow control 190, either adjustable or fixed, can be provided to restrict the flow of heat transfer fluid through the electric heater 180 to cause some of the heat transfer fluid to flow through the fluid circulation lines 162 rather than all of it flowing through the less restrictive electric heater 180.

In one aspect, the electric heater 180 can include twin thermostats 182, 184 wired in series to accommodate the flow of heat transfer fluid in both directions through the electric heater 180.

In one aspect, the flow control 190 can be set to only allow enough flow through the electric heater 180 to maximize the heat transferred by the electric heater 180 to the heat transfer fluid passing through the electric heater 180 while staying below the electric heater thermostat 182, 184 settings. This would force the remaining flow of heat transfer fluid through the first distribution manifold 140, the fluid circulation lines 162, and the second distribution manifold 150.

In one aspect, the flow control 190 could limit the flow of heat transfer fluid through the flow control 190 to 7 gpm (gallons per minute).

In operation, heated heat transfer fluid will be heated by the primary heater 120, and the circulation pump 130 will circulate this heated heat transfer fluid through the system 110. The heated heat transfer fluid will be circulated from the supply port 122 of the primary heater 120 to the intake port 172 of the flow reverser 170.

The flow reverser 170 can operatively connect the intake port 172 to either the first portion 176 or the second port 178. If the flow reverser 170 is first set to operably connect the intake port 172 to the first port 176, the heated heat transfer fluid will flow through the flow reverser 170 and out the first port 176 where the flow of heated heat transfer fluid will be divided, with a portion of the heat transfer fluid flowing to the first distribution manifold 140 and the rest of the heat transfer fluid flowing to the first accessory port 186, the flow control 190 and the electric heater 180.

If the flow control 190 is set to limit flow through the flow control 190 to 7 gpm and the flow of heat transfer fluid from the first port 176 of the flow reverser 170 is 22 gpm, than 7 gpm of flow of heat transfer fluid will flow through the first accessory port 186 to the electric heater 180 and 15 gpm of flow of heated heat transfer fluid will flow to the first distribution manifold 140.

For the portion of the flow of heat transfer fluid that is routed to the first distribution manifold 140, the first distribution manifold 140 will distribute the flow of heated heat transfer fluid to the plurality of fluid circulation lines 162 connected to the first distribution manifold 140. The heated heat transfer fluid can flow through each of the fluid circulation lines 162 and over the material 102 to be heated, transferring heat from the heated heat transfer fluid to the material 102 and cooling the heat transfer fluid as it passes through the fluid circulation lines 162, before it reaches the second distribution manifold 150 where it is combined back into a single flow and routed to the second port 178 of the flow reverser 170.

For the portion of the flow of heat transfer fluid that is routed to the electric heater 180, the electric heater 180 can further increase the temperature of the heat transfer fluid before is supplied back to the second accessory port 188 and then to the second port 178 of the flow reverser 170.

The flow of cooled heat transfer fluid from the second distribution manifold 150 and the flow of heated heat transfer fluid from the electric heater 180 will be combined before the combined flow is supplied to the second port 178 on the flow reverser 170. The mixing of the flow of heat transfer fluid, will result in a flow of heat transfer fluid that reaches the second port 178 at a higher temperature than the cooled heat transfer fluid from the second distribution manifold 150. For example, if the system 110 was being used for a 400,000 BTU ground thaw application with the primary heater 120 and the circulating pump 130 outputting 22 gpm of heat transfer fluid heated to 180° F., 7 gm of the heat transfer fluid would flow through the electric heater 180 and 15 gpm of heat transfer fluid would flow through the plurality of fluid circulation lines 162 making up the ground thaw grid. The 15 gpm of cooled fluid returning from the circulating fluid lines 162 will mix with the 7 gpm of heated heat transfer fluid coming from the electric heater 180 before being circulated back to the primary heater 120. If the cooled heat transfer fluid returning from the fluid circulation lines 162 was at 80° F. and mixes with the heated heat transfer fluid coming from the electric heater 180 that has been heated to 200° F., the blended 22 gpm flow of heat transfer fluid that is returned to the primary heater 120 can be 164° F.

In the flow reverser 170, the second port 178 can be operably connected to the outlet port 174 directing the flow of heat transfer back to the primary heater 120 to be further heated and circulated through the system 110 again.

The flow reverser 170 allows the direction of flow of heated heat transfer fluid through the fluid circulation lines 162 to be periodically reversed. When the heat transfer fluid only flows in one direction through the fluid circulation lines 162 the material 102 closer to inlet ends of the fluid circulation lines 162 where heated heat transfer fluid first enters the fluid circulation lines 162 will be heated faster than the material 2 closer to the outlet ends of the fluid circulation lines 162 because the heat transfer fluid will be transferring heat to the material 102 as it passes through the fluid circulation lines 162 and become cooler and cooler as it passes through the fluid circulation lines 162. At the outlet ends of the fluid circulation lines 162, the heat transfer fluid will likely be at its coolest before being circulated back to the primary heater 120. The result is that material 102 will be heated less the closer it is to the outlet ends of the fluid circulation lines 102.

By periodically reversing the direction of the flow of the heated heat transfer fluid through the fluid circulation lines 162 using the flow reverser 170, the material 102 can be more evenly heated. To reverse the direction of flow of the heat transfer fluid through the fluid circulation lines 162, the flow reverser 170 can change the direction of the flow of heat transfer fluid through the fluid circulation lines 162, switching the intake port 172 from being operatively connected to the first port 176 to the intake port 172 being operatively connected to the second port 178 and switching the outlet port 174 from being operatively connected to the second port 178 to the outlet port 174 being operatively connected to the first port 176.

When this flow reversal takes place, the flow of heat transfer fluid through the fluid circulation lines 162 would at first taper to a stop before tapering back to full flow in the opposite direction. The flow characteristics and temperatures would be the same or similar, just the opposite direction.

From the second port 178, a portion of the flow of heated heat transfer fluid will flow to the second distribution manifold 150 and the rest of the flow of heat transfer fluid will flow to the second accessory port 188, the electric heater 180, and the flow control 190. The flow limit set by the flow control 190 will still determine the amount of the flow that passes through the electric heater 180.

For the portion of the flow of heat transfer fluid that is routed to the second distribution manifold 150, the second distribution manifold 150 will distribute the flow of heated heat transfer fluid to the plurality of fluid circulation lines 162 connected to the second distribution supply manifold 150. The heated heat transfer fluid can flow through each of the fluid circulation lines 162 and over the material 102 to be heated, transferring heat from the heated heat transfer fluid to the material 102 and cooling the heat transfer fluid as it passes through the fluid circulation lines 162, before it reaches the first distribution manifold 140 where it is combined back into a single flow and routed to the first port 176 of the flow reverser 170 before being routed back to the return port 124 of the primary heater 120.

However, in this case, the material 102 closest to the ends of fluid circulation lines 162 connected to the second distribution manifold 150 will receive the most heat transfer from the heated heat transfer fluid, with the heat transfer fluid cooling as it passes along the fluid circulations lines 162 to the first distribution manifold 140.

For the portion of the flow of heat transfer fluid that is routed to the electric heater 180, the electric heater 180 can further increase the temperature of the heat transfer fluid before is supplied back to the first accessory port 186 and then to the first port 176 of the flow reverser 170.

The flow of cooled heat transfer fluid from the first distribution manifold 140 and the flow of heated transfer fluid from the electric heater 180 will be combined before the combined flow is supplied to the first port 176 on the flow reverser 170. With the mixing of the flow of heat transfer fluid, resulting in a flow of heat transfer fluid that reaches the first port 176 being at a higher temperature than the cooled heat transfer fluid from the first distribution manifold 140 alone.

In this manner, the direction of flow of heat transfer fluid through the fluid circulation lines 162 can be periodically reversed using the flow reverser 170 to result in a more uniform heating of the material 102 adjacent to the fluid circulating lines 162.

FIGS. 3 and 4 illustrate a circulating fluid system 210, similar to circulating fluid system 110, but including a flow switch 295 to provide “no flow” protection for the electric heater 280 to prevent a condition where there is no flow of heat transfer fluid through the electric heater 280 is still on and generating heat. To incorporate the flow switch 295 into the system 210, a flow rectifier 300 is provided to cause heat transfer fluid to flow through the electric heater 280 in only one direction, regardless of the flow direction instigated by a flow reverser 270. Typically, flow switches 295 are one directional and only able to operate with a fluid flow passing in one direction through them, if the direction of the flow is reversed, the flow switch 295 may not work. The incorporation of the flow rectifier 300 ensures the flow of heat transfer fluid through the flow switch 295 is always in the same direction, the direction that can activate the flow switch 295.

Like the circulating fluid system 110 shown in FIG. 2, the circulating fluid system 210 can include: a primary heater 220; a circulating pump 230; a plurality of fluid circulation lines 262; a flow reverser 270; a first distribution manifold 240; a second distribution manifold 250; a flow control 290; and, an electric heater 280. In addition, the circulating fluid system 210 can further include the flow switch 295; and a flow rectifier 300.

The primary heater 220 uses a fuel to supply energy and is capable of increasing the temperature of a heat transfer fluid, such as glycol, supplied to the primary heater 220. The primary heater 220 can have a supply port 222 where heat transfer fluid that has been heated by the primary heater 220 can exit the primary heater 220 and a return port 224 where heat transfer fluid can be returned to the primary heater 220.

The circulating pump 230 can work in conjunction with the primary heater 220, with the circulating pump 230 pressurizing the heat transfer fluid heated by the primary heater 220 so that the heat transfer fluid will flow out of the supply port 222 and through the system 210.

The flow reverser 270 can have an intake port 272 and an outlet port 274 with the intake port 272 being connectable to the supply port 222 of the primary heater 220 by a conduit and the outlet port 274 being connectable to the return port 224 of the primary heater 220 by a conduit so that pressurized heated heat transfer fluid from the supply port 222 can be supplied to intake port 272 of the flow reverser 270 and cooled heat transfer fluid can be routed from the outlet port 274 of the flow reverser 270 to the return port 224 of the primary heater 220.

The flow reverser 270 can also be provided with a first port 276 and a second port 278 and the flow reverser 270 can selectively alter the flow of heat transfer fluid through the flow reverser 270 by selecting between: a first direction, operably connecting the intake port 272 of the flow reverser with the first port 276 and operably connect the outlet port 274 of the flow reverser 270 to the second port 278; and, a second direction, operatively connecting the intake port 272 of the flow reverser 270 to the second port 278 and operatively connecting the outlet port 274 of the flow reverser 270 to the first port 276.

The first distribution manifold 240 can be connected by a conduit to the first port 276 and the second distribution manifold 250 can be connected by a conduit to the second port 278. The plurality of fluid circulation lines 262 can be connected between the first distribution manifold 240 and the second distribution manifold 250.

The flow rectifier 300 can be connected in parallel with the fluid circulation lines 262 by accessory ports 286, 288 and the flow control 290, the flow switch 295 and the electric heater 280 can be connected to the flow rectifier 300. The flow rectifier 300 can be used to ensure heat transfer fluid always flows through the electric heater 280 and the flow switch 295 in one direction, no matter what direction the flow reverser 270 is causing the heat transfer fluid to flow through the plurality of fluid circulation lines 262. The flow rectifier 300 can be operably connected between the accessory ports 286, 288 and the electric heater 280 to control the direction of flow to the electric heater 280.

The flow rectifier 300 can include a series of t-connections 310, 312, 314, 316 and check valves 321, 322, 323, 324 operative to rectify flow in a single direction to the electric heater 280. The flow rectifier 300 can have a first port 302, a second port 304, an output port 306 and an input port 308. The electric heater 280, the flow switch 295 and the flow control 290 can be connected inline to the output port 306 so that heat transfer fluid flowing from the output port 306 flows through the electric heater 280, the flow switch 295 and the flow control 290 before being returned to the input port 308. The first port 302 on the flow rectifier 300 can be operably connected to the first accessory port 286 and the second port 304 on the flow rectifier 300 can be operably connected to the second accessory port 288. The t-connections 310, 312, 314, 316 and one-way check valves 321, 322, 323, 324 can be used rectify the flow of heat transfer fluid through the flow rectifier 300. If there is a flow of heat transfer fluid in a first direction flowing into the flow rectifier 300 through the first port 302, the first port 302 can be operably connected to the outlet port 306 and the second port 304 with the input port 308, and when there is a flow of heat transfer fluid in a second direction flowing into the flow rectifier 300 through the second port 304, the second port 304 can be operably connected to the outlet port 306 and the first port 302 can be operably connected with the input port 308.

When the system 210 is circulating heat transfer through the fluid circulation lines 262 in the first direction, as shown in FIG. 3, heat transfer fluid can enter the fluid rectifier 300 through the first port 302. Check valve 324 can stop the flow of heat transfer fluid through the check valve 324, but the direction of the flow of heat transfer fluid can flow through the check valve 323 and out of the flow rectifier 300 through the output port 306 to the electric heater 280. Check valve 322 can stop the flow of heat transfer fluid through check valve 322, preventing flow to the second port 304. Heat transfer fluid that has flowed through the electric heater 280, the flow switch 295, and the flow control 290 and back to the flow rectifier 300 can flow back into the flow rectifier 300 through input port 308. Because of the natural pressure loss of the heat transfer fluid as it flows through the system 210, pressure on check valve 324 would be less from the flow of heat transfer fluid entering input port 308 than from the flow entering first port 302, keeping check valve 324 closed and stopping the flow through check valve 324. This flow of heat transfer fluid would then pass through check valve 321 and because of natural pressure loss again, the pressure of the flow of heat transfer fluid on check valve 322 from the heat transfer fluid entering the first port 302 will be higher than the flow of heat transfer fluid from the inlet port 308, keeping check valve 322 closed and causing the flow of heat transfer fluid to exit the second port 304 and flow back to the flow reverser 270.

When the flow reverser 270 is used to circulate heat transfer fluid through the fluid circulation lines 262 in the second direction, as shown in FIG. 4, heat transfer fluid can enter the fluid rectifier 300 through the second port 304. Check valve 321 can stop the flow of heat transfer fluid through the check valve 321, but the direction of the flow of heat transfer fluid can flow through the check valve 322. Check valve 323 can stop the flow of heat transfer fluid through check valve 323, causing the flow of heat transfer to flow out of the flow rectifier 300 through the output port 306 to the electric heater 280. Heat transfer fluid that has flowed through the electric heater 280, the flow switch 295, and the flow control 290 and back to the flow rectifier 300 can flow back into the flow rectifier 300 through input port 308. Because of the natural pressure loss of the heat transfer fluid as it flows through the system 210, the pressure on check valve 321 would be less from the flow of heat transfer fluid entering input port 308 than from the flow entering second port 304, keeping check valve 321 closed and stopping the flow through check valve 321. This flow of heat transfer fluid would then pass through check valve 324 and because of natural pressure loss again, the pressure of the flow of heat transfer fluid on check valve 323 from the heat transfer fluid entering the second port 304 will be higher than the flow of heat transfer fluid from the inlet port 308, keeping check valve 323 closed and causing the flow of heat transfer fluid to exit the first port 302 and flow back to the flow reverser 270.

Because the electric heater 280 will typically offer very little resistance to the flow of heat transfer fluid through the electric heater 280 compared to the resistance that would typically be created by the first distribution manifold 240, the fluid circulation lines 262 and the second distribution manifold 250, the flow control 290 can be provided to restrict the flow of heat transfer fluid through the electric heater 280 to cause heat transfer fluid to flow through the fluid circulation lines 262 rather than all of it flowing through the less restrictive electric heater 280.

The flow switch 295 can be provided proximate to the electric heater 280 and, in one aspect, downstream from the electric heater 280, but upstream from the flow control 290. The flow switch 295 can be a conventional flow switch and used to control the operation of the electric heater 280. When there is a flow of heat transfer fluid passing through the flow switch 295, engaging the flow switch 295, the electric heater 280 can be operating. However, if the flow of heat transfer fluid through the flow switch 295 stops, the flow switch 295 can stop the electric heater 280, preventing the electric heater 280 from energizing and possible element burnout when there is no flow of heat transfer fluid through the flow switch 295 and the electric heater 280.

In operation, heated heat transfer fluid will be heated by the primary heater 220, and the circulation pump 230 will circulate this heated heat transfer fluid through the system 210. The heated heat transfer fluid will be circulated from the supply port 222 of the primary heater 220 to the intake port 272 of the flow reverser 270.

The flow reverser 270 can operatively connect the intake port 272 to either the first port 276 or the second port 278. If the flow reverser 270 is first set to operating in the first direction, operably connecting the intake port 272 to the first port 276, as shown in FIG. 3, the heated heat transfer fluid will flow through the flow reverser 270 and out the first port 276 where the flow of heated heat transfer fluid will be divided, with a portion of the heat transfer fluid flowing to the first distribution manifold 240 and the rest of the heat transfer fluid flowing to the first accessory port 286 and the first port 302 of the flow rectifier 300.

For the portion of the flow of heat transfer fluid that is routed to the first distribution manifold 240, the first distribution manifold 240 will distribute the flow of heated heat transfer fluid to the plurality of fluid circulation lines 262 connected to the first distribution manifold 240. The heated heat transfer fluid can flow through each of the fluid circulation lines 262 and over the material 202 to be heated, transferring heat from the heated heat transfer fluid to the material 202 and cooling the heat transfer fluid as it passes through the fluid circulation lines 262, before it reaches the second distribution manifold 250 where it is combined back into a single flow and routed to the second port 278 of the flow reverser 270.

For the portion of the flow of heat transfer fluid that is routed through the flow rectifier 300, the flow rectifier 300 can operably connect the first port 302 with the outlet port 306 and operably connect the second port 304 with the input port 308 to have the flow of the heat transfer fluid flowing through the electric heater 280, the flow switch 295 and the flow control 290 before returning to the input port 308, in the proper direction for the flow switch 295 to operate properly. The flow can then exit the second port 304 before being routed back to the second accessory port 288 and then to the second port 278 of the flow reverser 270.

The flow of cooled heat transfer fluid from the second distribution manifold 250 and the flow of heated transfer fluid from the electric heater 280 and the flow rectifier 300 will be combined before the combined flow is supplied to the second port 278 on the flow reverser 270. The mixing of the flow of heat transfer fluid, will result in a flow of heat transfer fluid that reaches the second port 278 at a higher temperature than the cooled heat transfer fluid from the second distribution manifold 250.

In the flow reverser 270, the second port 278 can be operably connected to the outlet port 274 directing the flow of heat transfer back to the primary heater 220 to be further heated and circulated through the system 210 again.

The flow reverser 270 allows the direction of flow of heated heat transfer fluid through the fluid circulation lines 262 to be periodically reversed and the flow rectifier 300 causes the flow of heat transfer fluid through the electric heater 280 and the flow switch 295 to always be in the same direction, no matter what direction the flow reverser 270 is circulating the heat transfer fluid through the fluid circulation lines 262.

To reverse the direction of flow of the heat transfer fluid through the fluid circulation lines 262, the flow reverser 270 can change the direction of the flow through the fluid circulation lines 262, switching from the first direction, shown in FIG. 3, to the second direction, shown in FIG. 4, with the flow rectifier 300 causing the heat transfer fluid to flow through the electric heater 280 flowing in the same direction no matter what direction the flow reverser 270 is circulating the heat transfer fluid through the fluid circulation lines 262.

In the second direction, as shown in FIG. 4, the flow reverser 270 can operatively connect the intake port 272 to the second port 278 and the outlet port 274 to the first portion 276. Heated heat transfer fluid, supplied from the primary heater 220 will flow through the flow reverser 270 and out the second port 278 where the flow of heated heat transfer fluid will be divided, with a portion of the heat transfer fluid flowing to the second distribution manifold 250 and the rest of the heat transfer fluid flowing to the second accessory port 288 and the second port 304 of the flow rectifier 300.

For the portion of the flow of heat transfer fluid that is routed to the second distribution manifold 250, the second distribution manifold 250 will distribute the flow of heated heat transfer fluid to the plurality of fluid circulation lines 262 connected to the second distribution manifold 250. The heated heat transfer fluid can flow through each of the fluid circulation lines 262 and over the material 202 to be heated, transferring heat from the heated heat transfer fluid to the material 202 and cooling the heat transfer fluid as it passes through the fluid circulation lines 262, before it reaches the first distribution manifold 240 where it is combined back into a single flow and routed to the first port 276 of the flow reverser 270.

For the portion of the flow of heat transfer fluid that is routed through the flow rectifier 300, the flow rectifier 300 can operably connect the second port 304 with the outlet port 306 and operably connect the first port 302 with the input port 308 to have the flow of the heat transfer fluid flowing through the electric heater 280, the flow switch 295 and the flow control 290 before returning to the input port 308, in the proper direction for the flow switch 295 to operate properly. The flow can then exit the first port 302 before being routed back to the first accessory port 286 and then to the first port 276 of the flow reverser 270.

The flow of cooled heat transfer fluid from the first distribution manifold 240 and the flow of heated transfer fluid from the electric heater 280 and the flow rectifier 300 will be combined before the combined flow is supplied to the first port 276 on the flow reverser 270. The mixing of the flow of heat transfer fluid, will result in a flow of heat transfer fluid that reaches the first port 276 at a higher temperature than the cooled heat transfer fluid from the first distribution manifold 240.

In the flow reverser 270, the first port 276 can be operably connected to the outlet port 274 directing the flow of heat transfer back to the primary heater 220 to be further heated and circulated through the system 210 again.

If at any time, the flow switch 295 determines there is no flow of heat transfer fluid through it, the flow switch 295 can de-energize the electric heater 280.

In this manner, the flow reverser 270 can periodically alternate the direction of flow of heat transfer fluid through the fluid circulation lines 262 using the flow reverser 270 to result in more uniform heating of the material 202 adjacent to the fluid circulating lines 262 and the flow rectifier 300 can be used to ensure the flow of heat transfer fluid through the electric heater 280 and the flow switch 295 is always in the same direction so that the flow switch 295 operates properly, no matter the direction the heat transfer fluid is flowing through the fluid circulation lines 262.

The foregoing is considered as illustrative only of the principles of the invention. Further, since numerous changes and modifications will readily occur to those skilled in the art, it is not desired to limit the invention to the exact construction and operation shown and described, and accordingly, all such suitable changes or modifications in structure or operation which may be resorted to are intended to fall within the scope of the claimed invention.

PORTABLE HYBRID HYDRONIC HEATING SYSTEM

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CPC

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