Patent Application
20120298204
The present invention relates to an energy saving system and method, specifically to a system and method for heating water.
Supplying constant hot water is a major expense, especially for larger buildings such as hotels, health and country clubs. The cost of energy is continually rising and thus it has become more important to find better and more efficient systems and processes for saving energy and reducing costs.
Generally, power utility companies including electricity companies charge consumers and end users according to demand. That is, the cost of electricity may vary depending on the time of day to reflect the overall demand, so that if there is a 3-tier tariff, for example, the cost at peak rates may be several times higher than at normal rates. Additionally, to spread the load, utility companies may at low demand times, such as during the night, offer electricity at a much cheaper rate.
However, heating water at off-peak times and at a cheaper tariff is only efficient and effective if the water can be kept hot and be available on demand including during peak rate times. If the water cools down after being heated and then requires the use of peak rate electricity to heat/reheat the water, the cost of energy rises and any saving of energy may be dissipated.
It would, thus be advantageous to have an energy saving system which uses a cheaper energy source, such as low rate electricity, to supply constant hot water on demand at all times.
The present invention describes embodiments of an energy saving system and method for heating water. Cheaper utility costs are utilized for heating water and maintaining the temperature of the water for supplying to consumers/end users on demand.
A control system effectively controls the heating and supply of water. The control system may be configured to any of a group of criteria including the operating times for heating the water and the temperature to which the water is heated, the operating times and the amount of heated water to be stored in storage tanks for draw off by the user.
There is therefore provided, in accordance with an embodiment of the present invention a method for controlling the costs of heating water which includes the steps of: using heat pumps to heat water in a heating tank to a pre-determined maximum temperature; maintaining the temperature of the water in the heating tank between a pre-determined minimum temperature and the pre-determined maximum temperature; transferring the heated water to a storage tank; maintaining the temperature of the water in the storage tank within a pre-determined temperature range; and supplying the heated water under pressure to consumers, the heated water having a temperature within the pre-determined temperature range.
Furthermore, in accordance with an embodiment of the present invention, there is provided a method for controlling the costs of heating water. The method includes the steps of:
Furthermore, according to an embodiment of the invention, the step of maintaining the temperature of the water in the storage tank includes the step of transferring water heated by a solar collection system to the storage tank.
Furthermore, according to an embodiment of the invention, if the temperature of the water in the storage tank rises above the maximum temperature of the pre-determined temperature range; the method includes the step of adding water circulating within a pipe network connecting the consumers to the storage tank, thereby to reduce the temperature of the water in the storage tank to within the pre-determined temperature range.
Furthermore, according to an embodiment of the invention, the step of activating the at least one heat pump includes the steps of opening a valve connected to the main water supply and activating at least one circulating pump in communication with the heat pump, so that water may be heated by the heat pumps.
Furthermore, according to an embodiment of the invention, the method further includes the step of utilizing a control device to control the operation of the heat pumps and circulating pumps.
Furthermore, according to an embodiment of the invention, the step of maintaining the temperature of the water in the heating tank, further includes the steps of detecting any of a group of faults including heating pump failure, circulating pump failure, overheating of the water in the heating tank and level of water in the storage tank falling below a critical level; and alerting the control device if any of the group of faults is detected.
Furthermore, according to an embodiment of the invention, the method further includes the steps of:
Furthermore, according to an embodiment of the invention, the method further includes the steps of:
Furthermore, according to an embodiment of the invention, the method further includes the steps of:
Furthermore, according to an embodiment of the invention, the method further includes the steps of:
Additionally, there is also provided an energy saving system for controlling the costs of heating water, which includes at least one heating tank; at least one heat pump in communication with the heating tank, to heat water in the heating tank to a pre-determined temperature; at least one storage tank in communication with the heating tank to store water previously heated in the heating tank; at least one pressure pump in communication with the storage tank for supplying the heated water from the storage tank to consumers; a control device in communication with the heat pump; and a pipe network system connecting the at least one heating tank, the heating tank and the heat pump with consumers. The energy saving system is configured to maintain the temperature of the water within the storage tank and pipe network system within a pre-determined range.
Furthermore, according to an embodiment of the invention, the system further includes a solar water heating system in communication with the storage tank and the control device for supplementary heating of water in the storage tank.
Furthermore, according to an embodiment of the invention, the solar collection system includes an evacuated tube solar collector; the evacuated tube solar collector includes at least one heat transfer header, each heat transfer header having a plurality of vacuum tubes connected thereto.
Furthermore, according to an embodiment of the invention, the system further includes a heating coil fitted within the storage tank in communication with the storage tank and the control device for supplementary heating of water within the storage tank.
Furthermore, according to an embodiment of the invention, the system further includes a first thermostat for measuring the temperature of the water in the heating tank and a second thermostat for measuring the temperature of the water in the storage tank. The first and the second thermostats are in communication with the control device.
Furthermore, according to an embodiment of the invention, the system further includes a first transducer for determining the volume of water in the heating tank and a second transducer for determining the volume of water in the storage tank. The first and the second transducers are in communication with the control device.
Furthermore, according to an embodiment of the invention, if the second transducer indicates that the volume of water in the storage tank has dropped to a pre-determined minimum volume during periods of cheap rate tariff electricity, the heat pump is activated to heat water to the pre-determined temperature and the heated water is added to the storage tank, thereby to ensure that the volume of water in the storage tank remains greater than the pre-determined minimum volume.
Furthermore, according to an embodiment of the invention, if the second transducer indicates that the volume of water in the storage tank has dropped to a second minimum volume during periods of regular rate electricity, wherein the second minimum volume of water is less than the first minimum volume of water and wherein regular tariff electricity costs more than cheap rate tariff electricity, the heat pump is activated to heat water to the pre-determined temperature and the heated water is added to the storage tank thereby to ensure that the volume of water in the storage tank remains greater than the second minimum volume.
Furthermore, according to an embodiment of the invention, if the second transducer indicates that the volume of water in the storage tank has dropped to a third minimum volume during periods of peak rate electricity; wherein the third minimum volume of water is less than the second minimum volume of water and wherein peak tariff electricity costs more than regular rate tariff electricity, the heat pump is activated to heat water to the pre-determined temperature and the heated water is added to the storage tank, thereby to ensure that the volume of water in the storage tank remains greater than the third minimum volume.
The present invention will be understood and appreciated more fully from the following description taken in conjunction with the appended drawings in which:
This present invention relates to an energy saving system which utilizes cheaper utility costs for heating water. The system is configured to efficiently optimize the heating of water for all types of consumer, especially for apartment buildings having a common heating source, hotels, office buildings, health and country clubs. Efficiency and cost savings are achieved by a control system which is configured to alter one or more of group of criteria including the amount of water stored in the tanks, the temperature of the water and the operating times for heating and supplying water. The times for heating and supplying water may be adjusted to allow for the different demands dependent on the days of the week or seasons, as required. The heating system may be operated manually or automatically by the controller. The system is configured to efficiently heat water at a cheaper cost, such as by utilizing cheaper night-time electricity tariff, for example and maintaining the temperature of the water at the optimum temperature required for the user.
In any large system, a large amount of water remains in the water pipe network. If water is not drawn off, during night time, for example, the water in the pipes and the storage tanks cools. The present invention ensures that the water in the storage tank is maintained at the optimum temperature at a minimum cost.
Reference is now made to
In the embodiment of
The system 10 further comprises at least one heat pump 18 for heating the water in heating tank 12, at least one pressure pump (M4; M5), a plurality of circulating pumps (M1; M3), a plurality of taps (B1; B2; B3), a plurality of thermostats (T1, T2, T3 and T4), and a plurality of pressure transducers (L1; L2). Preferably at least two pumps should be used to ensure that the system has a backup in the event that one pump fails and for greater flexibility during heating periods.
B1 controls the inflow of water from the main water supply. B2 controls the flow of water into the storage tank 16. B3 controls the flow of water into the heating tank 16.
Thermostats may be installed to measure the temperature of the water at different places within the system. T1 may be installed in heating tank 12, T2 may be installed in storage tank 16, and T3 may measure the temperature of the water within a solar water heating system 22, described hereinbelow, while T4 may measure the temperature of the main water supply 14.
The level of water in heating tank 12 may be determined by pressure transducer L1 and the level of water in the storage tank 16 may be determined by pressure transducer L2.
The system 10 further comprises a controller 24 which may be in communication with all the operating elements of the system including, but not limited to the heat pumps 18, pressure and circulating pumps, valves, thermostats and pressure transducers. The controller 24 may be any suitable controller, such as a computerized control system, known in the art having processing capabilities. The controller may be directly connected or configured to communicate remotely, via the Internet, for example, to the operating elements of the system. The controller 24 may control the operation of the various components of the system 10, such as the operation of the heating pumps, transfer of heated water to the storage tank and thence to the customers, as well as controlling the operation of the thermostats, for example.
The pressure pumps M4 and M5 may be activated to only provide water to consumers during specific times, which may be effected by connecting a 24 hour timer to the controller 24.
Preferably, storage tank 16 has a much greater capacity than tank 12. In an embodiment of the system, storage tank 16 may be approximately three times larger than heating tank 12. Heating tank 12 and storage tank 16 are preferably insulated to ensure that the water in the tanks does not cool too quickly.
The water in heating tank 12 is heated by means of the heat pumps 18. Basically, heat pumps are extremely efficient, since they transfer heat, rather than burn fuel to create it.
Any type of heat pump, known in the art, may be used, such as air-air heat pumps, air-source heat pumps, ground-source heat pumps, that absorb heat from the ground or an underground body of water and transfer it indoors, or vice versa. Absorption heat pumps are air-source heat pumps that are powered by natural gas, solar power rather than by electricity. Briefly, a heat pump is a device that uses a small amount of energy to move heat from one location to another. Heat pumps are usually used to pull heat out of the air or ground to heat a home or office building, or they can be switched into reverse to cool a building. Heat pumps work extremely efficiently, because they simply transfer heat, rather than burn fuel to create it.
Optionally, the system may also comprise a heating coil 20 fitted within storage tank 16 for supplementary heating of water within the storage tank 16.
Optionally, the system may also comprise a solar water heating system 22, which comprises vacuum tubes (or solar panels) which absorb thermal energy from the sun and convert it into usable heat. The solar water heating system 22 may be connected to the storage tank 16, a shown, and water circulated by means of pressure pump M3. While any solar water heating system, known in the art may be used, a solar water heating system 22 using evacuated tubes is preferred.
Briefly, in an evacuated tube solar collector (as illustrated in
Solar tubes have better insulation properties than flat plate solar collectors since the inner tube is insulated from heat loss. Once heat is absorbed, it is transferred to the water in the manifold, and not lost to the outside environment. Combined with the heat transfer efficiency of the heat pipe, the solar collector can deliver excellent heat output all year round.
The system 10 may be configured to record all measurements associated with the system's operation, such as the amount of energy needed, by metering the water data, the temperature differences recorded by T2 during filling of storage tank 16 and by T4 during inflow of mains water, and the electric consumption of the system. Additionally, the amount of water supplied to consumers and the electricity consumption according to various tariff rates may be recorded. All measurements may be stored in a memory device for analysis and further processing.
In one embodiment, water enters the system 10 during periods of cheaper electricity, for example and is diverted, to the heat pumps 18, which heat the water to the desired pre-determined temperature. The heated water is pumped into the main heating tank 12.
Heat pumps 18 control the heating of the water, so that while the tank is being filled, the temperature in the heating tank 12 does not drop below a pre-determined minimum temperature. For example, thermostat T1, installed in heating tank 12, may be used to control the heating process. If the temperature in tank 12 doesn't rise above 0.2° C. for five minutes (say) and the temperature in the tank 12 is above 56° C. (for example), the heating process may be considered to be complete and the water is hot enough to be transferred to storage tank 16.
Thermostat T1 may also be used to detect a fault in the system. For example, if the temperature in the tank 12 is below 52° C. (for example), while heat pumps 18 are in action and for a period of five minutes (say), the temperature does not rise above 0.2° C. (say), this is indicative of a potential fault with the heating pump and an alert may be sent to the controller.
When the heating tank 12 reaches a pre-determined temperature, the heat pump 18 ceases operating. Heat pump 18 primarily operates during the cheaper tariff periods, whenever the water in the tank falls below the desired temperature. The heat pump is not normally activated during the daytime when electricity rates are higher.
The heat pumps 18 may be configured, in certain scenarios, to also operate during peak charge electricity periods, as will be described hereinbelow. Normally, during daytime, when the hot water is drawn off, the system shuts off the cold water inflow, so that cold water will not enter the tanks. Thus, the water in the tank remains at or close to its heated temperature.
However, in certain scenarios, the heat pumps may be used during peak times, as will be described hereinbelow. For example, in an alternative embodiment of the invention, if the water in the tanks runs out before the pumps are re-activated (during at the times of the lower tariff), water may be allowed to enter the system at a controlled amount, say up to a maximum of 10-15% (for example) of the volume of the tank. The heat pump may then be activated to heat up the minimum amount of (more expensive) water and thus ensure that hot water is always available. The latter operation may be repeated as necessary until the cheaper tariff rate comes into effect.
Once the temperature of the water, as measured by thermostat T5 has reached a pre-determined temperature, for example 60° C., the heated water (which may have a slightly lower temperature) is transferred to the storage tank 16, provided there is capacity.
In operation, water from the mains water supply 14 enters the system 10 via a water meter 25 and tap B1. The water may be pre-treated against furring (the build-up of lime-scale (calcium) and sediment, for example. A thermostat T4 measures the incoming water temperature. When B1 is opened, one or more of the heat pumps 18 are activated. The number of pumps activated may depend on the time programmed to fill tank 12 to its maximum capacity. The level of water in the tank 12 may be determined by pressure transducer L1.
The heat pumps 18 activate circulating pump M1, so that water enters the tank 12 via thermostat T5 and tap B3 (as indicated by arrows 26, 27, and 28). Circulating pump M1 is automatically activated by heat pumps 18 and not by the controller 24. Once the tank 12 is filled to its capacity (determined by pressure transducer L1), inlet tap B1 is closed and the water, circulated by pump M1 (as indicated by arrows 29, 26, 27, 28) is heated up by heat pumps 18. A circuit breaker 40 may be placed at the top of the tank to prevent overflowing. Circuit breaker 40 acts to shut off tap B3 when the tank 12 is full.
Once the maximum capacity of water reaches its pre-determined temperature (for example 60° C.) and the temperature (measured by thermostat T1) in tank 12 doesn't change by a pre-determined amount (say, 0.3° C.) for a pre-determined period (say 5 minutes, for example), heat pumps 18 cease operating.
As best seen in
Once the majority of the heated water in tank 12 has been transferred to storage tank 16, the heating process may be restarted; by reopening tap B1 and switching pumps 18 on. Thermostat T2 measures the temperature of the water in storage tank 16.
Tank 12 is filled and heated to the pre-determined temperature (say 60° C.), as described hereinabove. The process may be repeated until heating tank 12 and storage tank 16 are both full of heated water. A circuit breaker 42 may be placed at the top of the storage tank 16 to avoid water overflowing from the tank. Circuit breaker 42 acts to shut off tap B1 when the tank 16 is full.
The heated water is provided to consumers from the bottom of the tank (as indicated by the arrow 44) along water supply pipe by means of pressure pumps M4 and M5, through the consumer's water network. The supply of water may be activated to provide water to consumers only during specific times, as determined by a timer in communication with the controller. The water circulates within the consumer's water network and cools down within the pipe network. If the water in storage tank 16 is hot enough (that is above a pre-determined minimum temperature) the circulated water returns to the storage tank 16 (as indicated by arrows 46 and 48) provided that the temperature at water is not lowered below pre-determined minimum temperature. If the water in storage tank 16 is not hot enough to be cooled by the circulated water, the circulated water returns to the heating circuit (as indicated by arrows 46, 50 and 29).
The heating process may be adjusted by changing settings and times, for example, for each heating system suited to the specific requirements of a client. Thus, heating of water in tank 12 and discharging of heated water from storage tank 16 may be activated together or at different times.
Furthermore, a lack or excess of water in storage tank 16 may change the functioning of the pumps according to a preset program.
In an embodiment of the system having a solar collection system 22 connected thereto, the solar collection system 22 may be used to heat and maintain the water in tank 16 at the desired temperature. For example, if the temperature (measured by thermostat T3) of the water in the solar tubes is within a pre-determined range (say 2-7° C., for example), hotter than the water in storage tank 16 (measured by thermostat T2), pump M3 may be activated to transfer hot water to storage tank 16.
If the temperature in the tanks rises upon the required temperature, because of the heat from the solar collector system 22, cold water may be added (by opening tap B2) to prevent over-heating of the system.
Transfer of Water from Heating Tank to Storage Tank
The transfer of hot water from tank 12 to storage tank 16 may be optimized and configured according to varying parameters. Reference is now made to
The heating tank is filled with water and heated by the heat pumps 18 until the water reaches the desired temperature (say at 60° C., for example) (Step 202).
Once the water reaches the desired temperature (query box 204), and If there is room in the storage tank 16 (query box 206), the heated water may be transferred to the storage tank 16 (step 208).
The heating/transfer operation (steps 202 to 208) continues until the storage tank 16 is full of heated water. If both the heating tank 12 and storage tank 16 are full of heated water, the heating/transfer operation ceases (step 210).
In order to obtain the maximum energy saving, the water should only be heated up during periods of cheap rate electricity, usually during the night when there is a very low consumer demand and thus a very low or nil draw-off of water from the storage tank 16 by the consumer 17. Since the greater consumer demand and draw-off of heated water occurs during the periods of standard or peak tariff, the volume of water in the storage tank 16 will gradually be reduced. In order to conserve energy, preferably the heat pumps will only be operated during non-cheap tariff periods, if the volume of water in the storage tank 16 drops to a pre-determined level.
Thus, during peak tariff periods (query box 212), the volume of water may be allowed to drop to 40-50% of capacity (say less than 45% full)−(query box 218), before the heat pumps are activated to heat water in the heating tank 12. The heating/transfer operation will then be activated (steps 202 to 208).
During standard tariff periods (query box 214), which is normally cheaper than peak tariff rates, a greater volume of water may be heated at standard rates compared with peak rates. Thus, the heat pumps may be activated to heat water in the heating tank 12 when the volume drops below 60% (between 50-60%) of capacity (query box 218). The heating/transfer operation will then be activated (steps 202 to 208) to fill the storage tank 16.
During cheap rate tariff periods (query box 216), the heat pumps may be activated to heat water in the heating tank 12 at any time to maintain full capacity (query box 222).
Preferably, heat pumps 18 comprise at least two pump units. In this case, each pump may be set to heat the water in tank 12 separately, at different times. For example, at night, when water consumption is low and electricity rates are cheaper, the pumps 18 may be activated to heat the water so as to maintain maximum volume of heated water in storage tank 16. In the morning, the volume alert level in storage tank 16 may be set to any desired value, for example, 45% to 95%, depending on demand and the tariff rates.
In an embodiment of the present invention, all the available pumps 18 may be activated so as to preserve the maximum volume of heated water in storage tank 16 prior to the onset of the peak tariff rate. The pumps 18 may be activated according to the following exemplary criteria:
The second pump may be automatically activated at low and high tariff times only. At peak tariff, the second pump may only be activated if the volume of water in storage tank 16 has dropped to 30% of capacity.
The settings and times may be adjusted according to the type of client (country club, hotel, retirement home, for example), taking into account the electric tariff rates, the seasons and days of the week.
In an embodiment of the present invention, the water may be heated continuously. In this case, the pumps may be activated according to low-high tariff rates, without being active at peak tariff rates, for example. The volume of water in the storage tank 16 may be set to be (say 75% to 98% of maximum capacity) before heating process ceases owing to the onset of peak tariff rates.
At low tariff, both pumps 18 may be activated. At high tariff the pumps may be activated to preserve a pre set water volume capacity (say, 70%-95%, for example) before the heating process ceases due to the onset of peak tariff rates. Generally, peak tariff rates last for 6 hours and thus, the system may be configured to so that water is not heated during a set period.
In this embodiment, if, during peak times the water volume capacity in storage tank 16 falls below 30% (say) and the temperature in heating tank 12 is below 55° C., the heating pumps may be activated to raise the temp to a minimum of 55° C. so that heated water may be transferred to storage tank 16.
If the water the temperature in heating tank 12 is above 55° C., the heated water will be transferred to storage tank 16, without the need to activate the heating pumps during peak tariff times.
If, after transfer, the water volume capacity in storage tank 16 falls below 30% (say), the filling and heating operation of tank 12 will start immediately, as described hereinabove.
Peak tariff in spring and autumn may be considered to be high tariff. It is then necessary to choose a period of 6 (say) hours which will be considered as peak tariff, when the system will not be active. For example, peak tariff may be between 11 am and 17:00 or between 9 am-12:00 and 14:00-17:00.
In a further embodiment of the present invention, using at least two pumps, the water may be heated by one pump, while the second pump (where there are two pumps) may be used for cooling or air-conditioning the building. The heat pumps maybe used for cooling by reversing the refrigeration cycle.
The activation times of each pump may be set separately according to seasons. For example, at night the cooling pump won't be active (especially during winter). Since the pumps are primarily for heating water, cooling is secondary consideration.
Activation times may be programmed for a year in advance according to tariff rates and the seasons. Peak rates during spring and autumn may be considered as high rate, apart from the rest period—which will be considered as peak tariff.
The volume of water in the storage tank 16 determines the activation of the pumps. If the volume of water in storage tank 16 is in the range of 30% to 90%, the pumps will be operated according to the heating process 1, described hereinabove.
If the volume of water in storage tank 16 falls below 30% and the temperature of the water in tank 12 is below 55° C., both heat pumps 18 will be activated. As soon as the temperature of the water rises to 55° C., the water will be transferred to storage tank 16.
When the volume of water in storage tank 16 is above 85%, the cooling pump may be activated. When the volume of water in storage tank 16 reaches 98% of capacity, and the water in heating tank 12 has reached its pre-determined temperature (say, 60° C.), the heating/cooling process will cease until the water is transferred from heating tank 12 to storage tank 16.
By activating one or the pumps for cooling/air conditioning of the building, the heat pump is reversed so that the water in the heating tank 12 may be heated up. Once the water has reached its pre-determined temperature (say, 60° C.), the ‘cooling’ pump ceases its cooling action and the heated water is transferred to storage tank 16. After the water has been transferred, the filling and heating operation will start again.
In a further embodiment of the present invention, water may be heated by utilizing reverse cycle air conditioning units that are being used to cool a building, for example. Since the reverse of the cooling process is the extraction of heat, the heat generated by the cooling process of the air-conditioner may be utilized to heat the water within the heating tank 12. Effectively, since heating is a nil-cost by product of the air conditioning, the cost of heating is reduced to almost zero, producing very ‘green’ technology.
Using at least two pumps, the water may be heated by one pump, while the second pump (where there are two pumps) may be used for cooling or air-conditioning the building. The heat pumps maybe used for cooling by reversing the refrigeration cycle.
A heating coil 20 may be fitted within storage tank 16 for supplementary heating of water within the storage tank 16. Heating coil 20 preserves the heat of the water in storage tank 16 and may be automatically activated, according to prevalent electric tariffs. Thus, in an exemplary embodiment, at night when low tariff is available, the heating element is used to maintain the temperature at 60° C. (say) in the tank. At night, the heating element 20 may be activated whenever the temperature of the water drops below 59° C., for example. During periods of high tariff rates, the heating element 20 may be activated whenever the temperature of the water drops below 54° C. and 50°.
In all situations, the heating element 20 will not be activated whenever the volume of water in the tank drops below 20% of capacity.
A plurality of alarms may be connected to the system 10. Non-limiting examples of alarms which may be activated, include the following:
Any type of alarm or combination of alarms, known in the art, may be utilized.
The tanks 12 and 16 may be any size, preferably to store a sufficient volume of water for daily consumption. The tanks may be constructed of any suitable material including fiberglass, PVC and metal, for example. Generally but not essentially, the heating tank 12 would have a smaller capacity than the first tank.
The heating operation may be repeated daily, all year round, automatically, and may be monitored by a computerized control system.
It will be appreciated that the present invention is not limited by what has been described hereinabove and that numerous modifications, all of which fall within the scope of the present invention, exist. Rather the scope of the invention is defined by the claims, which follow:
