Patent Application
20230375226
The present disclosure relates generally to forced air heaters with or without thermostats.
Conventional heaters typically generate and disseminate (distribute) heat by forced convection, that is, by blowing air over a heat source, and in particular by blowing air parallel to the base and extended surfaces of the heat source. This method of heat generation and dissemination is not always effective. Conventional heaters may lack sufficient heat distribution per given area in heating appliances. There may also be a lack of sufficient heat extraction from positive temperature coefficient (PTC) based heat source assemblies per given area of heat distributers in conventional heating appliances.
Further, restrictions in the discharged airflow dynamics in conventional heating appliances may lead to non-uniform heating and creating large temperature gradients in spaces and/or objects to be heated associated with the heater, leading to the reduction of the heat source's ability to generate and/or distribute heat. Conventional heaters may have limited operational and functional reliability. Conventional heaters may have a large physical size and may have ineffective heat distribution.
Conventional heaters also typically include a thermostat having a temperature sensor exposed to the environment in order to sense the temperature of the surrounding environment. This is generally used to allow the heater to turn off/on based on the temperature in the surrounding environment. In these conventional heating devices there may be an unnecessarily large number of thermostat cycling as a result of the thermostat's quick response to temperature changes due to relative low thermal mass of the thermostat's electrical contacts. Unnecessary thermostat cycling may shorten the life of the thermostat. An excessive amount of cycling may not allow objects to be heated which are associated with the heater or in the space serviced by the heater to reach a desired target temperature. When the life of thermostat is compromised with unnecessary thermostat cycling, this can also decrease the reliability of the heater.
Additionally, conventional heating appliances with excessive cycling may have a high thermostat contact temperature at startup due to high startup electrical current. Again, the excessive and unnecessary cycling of a thermostat can result in reduced thermostat service life.
It is, therefore, desirable to provide an improved heater.
It is an object of the present disclosure to obviate or mitigate at least one disadvantage of conventional forced air heaters.
There is provided a method and system for heating, and in particular a forced air heater having impingement airflow heat transfer from a heat source. In some cases, the heat source is a positive temperature coefficient (PTC) heat source. In some cases the heater has multiple air movers providing impingement airflow to transfer and extract heat from the heat source.
In an aspect herein, there is provided a forced air heater including: a heating element; a heat sink mounted on the heating element; and an air mover directing air towards the heating element such that the directed air provides impinged airflow in relation to the heating element.
In a particular case, the heat sink has at least one extended surface extending approximately in the direction of the air directed from the air mover.
In a particular case, the air mover directs the air such that the angle of impingement is an acute angle relative to the heating element.
In a further particular case, the angle of impingement is between 30 and 60 degrees relative to the heating element.
In a particular case, the air mover comprises a plurality of air movers and each air mover directs air towards the heating element at a same or different angle.
In a further particular case, the plurality of the air movers comprises two air movers and each air mover directs air towards the heating element from opposite sides of the heating element.
In a particular case, the heating element is a positive temperature coefficient (PTC) heating element.
In a particular case, the heating element and the heat sink are configured such that air directed at the heating element contacts the heating element or the heat sink and is then directed in multiple directions out of a body of the heater.
In a particular case, the heater of claim 1, further comprising a temperature sensing device wherein the temperature sensing device is thermally coupled with a solid heat-conductive object in the environment to be heated.
In a particular case, the temperature sensing device includes: a sensing plate mounted on the solid heat-conductive object in the environment to be heated; and an electrical contact connected to the sensing plate, wherein the electrical contact is thermally coupled with the heat-conductive object via the sensing plate.
In another aspect, there is provided a heater which includes a temperature sensing device, the temperature sensing device includes: a sensing plate mounted on a solid heat-conductive object in the environment to be heated; and an electrical contact connected to the sensing plate, wherein the electrical contact is thermally coupled With the heat-conductive object via the sensing plate.
In a particular case, the solid heat-conductive object in the environment to be heated comprises a solid heat-conductive component of the heater.
In a particular case, the solid heat-conductive object in the environment to be heated is metallic.
In another aspect, there is provided a method of controlling a heater, the method including: mounting a temperature sensing device such that it is thermally connected to a solid object in the environment to be heated; monitoring the temperature via the temperature sensing device; turning the heater on when the temperature from the temperature sensing device is below a first temperature threshold; and turning the heater off when the temperature from the temperature sensing device is above a second temperature threshold.
In a particular case, the solid object in the environment to be heated comprises a solid component of the heater.
In a particular case, the solid object in the environment to be heated comprises a metallic object.
In a particular case, the metallic object comprises a metallic component of the heater.
Other aspects and features of the present disclosure will become apparent to those ordinarily skilled in the art upon review of the following description of specific embodiments in conjunction with the accompanying figures.
Embodiments of the present disclosure will now be described, by way of example only, with reference to the attached Figures.
Generally, the present disclosure provides an improved forced air heater and method for heating and more specifically to an impingement heater and a method for temperature control in heating.
The heat sink 18 has a base 26 and extended surfaces or fins 28. The base 26 is mounted on the heating element 16 and the extended surfaces 28 project away from the base 26. In the example of
The impinged airflow may provide versatility in discharging airflow dynamics. Discharged impinged airflow 24 may be diverted to multiple directions such as out of the sides, top, and bottom of the heater 10. With warm air exiting in multiple directions, the air in the environment and heat-conductive solid objects in the environment are intended to become more uniformly heated preventing or reducing large temperature gradients in the environment or solid objects in the environment. The term “solid objects in the environment” is intended to refer to thermal masses that may be present in the area or environment to be heated other than the general air or gas in the environment and may include liquids or liquid-containing objects.
In an embodiment, the heat sink 18 may alternatively include a cross-cut heat distributer or a Pin Fin distributer in which the extended surfaces 28 of the heat sink 18 have cross-cuts to allow airflow perpendicular to the extended surfaces. In this case, the discharged airflow may be directed in additional directions along axes normal to the direction of the flow. The omni-directionality of the heater 10 allows for thermal mixing in the environment and is intended to provide more uniform thermal distribution of air in the environment.
In contrast, in impinged airflow, as described herein, the thermal and hydraulic boundary layers are generally broken at the point of contact and the local heat transfer coefficients are increased. It is intended that this results in higher heat transfer compared with conventional parallel flow.
The angle of impingement need not be exactly perpendicular to the base 26. For example,
The embodiment of
In some cases, the heating element 16 may be a positive temperature coefficient (PTC) heating element. Where a PTC heating element 16 is the heat source, an increase in heat removal translates to a higher heat output, which may increase heat extraction. The PTC heating element self-regulates as the output of the PTC heater depends on the temperature encountered by the PTC heater. As heat is extracted from the PTC heating element 16 by the impinged airflow 30, the PTC heating element 16 will draw more power to provide more heat compared to conventional heaters. The additional heat can then be removed by subsequent impinged airflow 30 directed at the heating element 16. Therefore, with use of PTC heating elements, it is intended that impinged airflow heat transfer increases heat distribution and extracts a higher amount of heat out of the heating elements.
In some applications, the heater 10 may be used where heating failure is not desirable. The reliability of the designed system generally increases with the number of air moving devices 20.
Multi-directionality of airflow may also aid in heat distribution. Multiple air movers 20 and the use of the impingement technology described herein is intended to provide comparable performance to those of conventional heaters but with smaller footprints. This becomes important for applications where there is limited space, such as in marine applications. Where the heater 10 has a plurality of air moving devices 20 there is intended to be an increase in heat distribution and heat extraction as well as an increase in reliability of the heater.
Airflow redundancy may also include targeting the heating element 16, and/or a heat sink 18 provided thereto, from different sides and directions. This is intended to translate into further heat removal and higher heat distribution to the ambient air. The number of air moving devices is not limited to two but could be any appropriate number and the direction of airflow could be from multiple sides and angles.
Referring again to
The thermal mass of the thermostat's electrical contacts when in contact with the body 37 is larger than that of the electrical contacts of the thermostat 36 when left in free air and as such the thermostat 36 may not respond as quickly to changes in temperature. Connecting the thermostat 36 to the body 37 increases the thermal mass but also heat sinking the contacts. Heat sinking the contacts is intended to thereby reduce the cycling of the thermostat 36 and prolong the life of the thermostat 36. Further, positioning the thermostat on a metallic body 37 is intended to provide more realistic temperature sensing in a situation where a solid object is being heated, such as, for example, heating an engine in a marine vehicle. This arrangement is intended to allow targeted objects to be heated faster and reach a desired target temperature faster and reduce the number of thermostat cycles.
) Thermally coupling the thermostat 36 to the body 37 is intended to enhance the thermostat's sensing capability, reduce excessive cycling, lengthen the on-time duration of cycles, and reduce the thermostat's contact temperature at startup. These improvements may increase the service life of the thermostat 36 and the temperature control system, thus increasing reliability of the heater 10.
) In conventional systems, where the temperature control system is designed to sense air temperature, the system's thermostat may react quickly in response to temperature changes and frequently activate and de-activate the heating system, with a short on-off cycle time. In this case, the contacts of the thermostat could become excessively hot due to frequent start-ups, which may shorten the life of the thermostat and decrease reliability of the heater. In addition, short cycle duration may not allow solid objects in the environment, which may already be lagging thermally, to absorb the energy required to reach a desired temperature.
With the thermostat 36 described herein, the temperature that is sensed is the temperature of a solid object 37 which is generally more settled and dampened in fluctuation than the surrounding air. By placing the thermostat 36 in contact with the metallic body 37, at startup, the heat that is generated in the thermostat's contacts is sinked and quickly distributes onto the metal body 37, protecting the thermostat 36 against excessive heat and prolonging its service life.
In some cases, the thermostat 36 may be sealed such that the thermostat 16 is not exposed to the surrounding environment. Having the thermostat 36 sealed is intended to protect the thermostat 36 from the hazardous environment and vice versa. In an example, where the heater 10 is located in an engine compartment, it is intended that a hermetically sealed thermostat 36 will be incapable of creating an exposed electrical arc that can react with fuel fumes in the compartment as the thermostat 36 is not in contact with the surrounding environment.
The cycling of the heater is then controlled by a controller. The controller may be, for example, a processor, microcontroller, programmable logic controller (PLC), a mechanical temperature control and/or regulating device, or the like. The controller 902 may be connected to, or form part of, another system; for example, an engine control unit. At 84, the controller reads the temperature readings provided by the heat sunk electrical contacts. At 86, the controller determines whether the temperature of the electrical contact readings are below a predetermined temperature threshold. At 88, if the temperature reading was below the predetermined temperature threshold, the controller activates the heater 10. At 90, the controller determines whether the temperature of the electrical contact readings is above a predetermined safety temperature threshold. At 92, if the temperature reading was above the predetermined safety temperature threshold, the controller deactivates the heater 10. In further embodiments, particularly where the heating element is self-regulating, the controller may not perform a determination with regard to the predetermined safety threshold at 90. In this case, if the temperature is not below the predetermined temperature threshold at 86, the controller will return to reading the temperature of the electrical contacts at 84.
In some cases, the heater 10 may be configured to operate at a temperature below the auto-ignition temperature of fuel fumes in the surrounding environment. This configuration may be accomplished by, for example, selecting a predetermined safety temperature threshold below the auto-ignition temperature, selecting a self-regulating heating element that operates below the auto-ignition temperature, or the like. It is intended that operating at a temperature below the auto-ignition temperature can prevent explosions or the like.
In a particular application, the heater 10 may be used in marine applications to maintain a desirable (e.g. above freezing) temperature in a particular environment or for a particular solid object in the environment, for example, an engine compartment or engine. In this case, the heater may provide improved fail-safe heating for an object (e.g. a boat engine) having a large thermal mass in a small space.
In an aspect, the present disclosure provides a heater having impingement airflow onto a heat sink with extended surfaces which is intended to increase heat transfer from a heat source to the ambient air by enhancing the heat transfer coefficient.
In an aspect, the present disclosure provides a heater having impingement airflow onto a PTC heat source assembly intended to increase heat extraction from PTC heating elements by increasing the rate of heat removal from the PTC and transferring it to the ambient.
In another aspect, the present disclosure provides a heater having a plurality of air moving devices (fans, blowers, etc.) intended to increase heat distribution, heat extraction, and reliability.
In yet another aspect, the present disclosure provides a heater having impingement airflow onto a heat source and heat sink assembly, and multiple air moving devices intended to enhance heat removal and heat extraction.
An intended advantage of the present disclosure is that the heater configuration provides improved heat extraction which may allow smaller components to be used. As well, a multiple fan configuration allows for a redundant ignition proof heater with omni-directional airflow smaller than conventional heater systems.
An intended advantage of the thermal mass thermostat configuration is that it allows the thermostat to be a better thermal proxy for components, for example those in an engine compartment, to protect the components from freezing, without the typically frequent thermostat cycling of conventional systems.
In the preceding description, for purposes of explanation, numerous details are set forth in order to provide a thorough understanding of the embodiments. However, it will be apparent to one skilled in the art that these specific details may not be required. In other instances, well-known structures and circuits are shown in block diagram form in order not to obscure the understanding. For example, specific details are not provided as to whether the embodiments described herein are implemented as a software routine, hardware circuit, firmware, or a combination thereof.
Embodiments of the disclosure can be represented as a computer program product stored in a machine-readable medium (also referred to as a computer-readable medium, a processor-readable medium, or a computer usable medium having a computer-readable program code embodied therein). The machine-readable medium can be any suitable tangible, non-transitory medium, including magnetic, optical, or electrical storage medium including a diskette, compact disk read only memory (CD-ROM), memory device (volatile or non-volatile), or similar storage mechanism. The machine-readable medium can contain various sets of instructions, code sequences, configuration information, or other data, which, when executed, cause a processor to perform steps in a method according to an embodiment of the disclosure. Those of ordinary skill in the art will appreciate that other instructions and operations necessary to implement the described implementations can also be stored on the machine-readable medium. The instructions stored on the machine-readable medium can be executed by a processor or other suitable processing device, and can interface with circuitry to perform the described tasks.
The above-described embodiments are intended to be examples only. Alterations, modifications and variations can be effected to the particular embodiments by those of skill in the art. The scope of the claims should not be limited by the particular embodiments set forth herein, but should be construed in a manner consistent with the specification as a whole.
| Number | Date | Country | |
|---|---|---|---|
| 61859965 | Jul 2013 | US |
| Number | Date | Country | |
|---|---|---|---|
| Parent | 14446455 | Jul 2014 | US |
| Child | 18366013 | US |
