SOLAR DRIVEN EJECTOR HEAT PUMPS FOR SUPPLEMENTAL HEATING AND COOLING RESOURCES
In one embodiment, solar-thermal system is provided. The solar-thermal system comprises a generator component; an evaporator component; a heat pump ejector comprising a mixing chamber; said heat pump ejector coupled to the generator component and the evaporator component; wherein the generator component emits a vapor stream into said mixing chamber and the heat pump ejector is configured to extract a working fluid vapor from the evaporator component into said mixing chamber through entrainment thereby to form a mixed flow; and a condenser component configured to cool said mixed flow via a cooling loop.
Embodiments of the invention relate to heating and cooling systems.
BACKGROUNDEjector heat pumps (EHPs) are a decades old technology that was and is applied to refrigeration and air conditioning applications. The common principle behind so-called Rankine refrigeration cycles is that a working fluid (i.e. the refrigerant) can be used to move heat from a lower temperature location to a warmer external environment by compressing the working fluid to raise its temperature above the external environment and subsequently expanding it to drop its temperature to provide the cooling effect. EHPs operate on this principle utilizing a vapor ejector with no moving parts to compress the working fluid instead of a mechanical compressor.
Referring to
Ejector heat pumps are appealing for several reasons, including the fact that the device functions as a compressor without any moving parts leading to increased reliability, longer lifetimes, and potentially lower costs than compressors with moving parts. One of the challenges of ejector heat pumps is that its coefficient of performance (COP) is lower than that of a mechanical compressor-based heat pump. The COP is defined as the ratio of energy input to energy transferred. A COP of 1.5 uses 1 unit of energy to move 1.5 units of heat. EHPs are generally capable of achieving COPs as high as 1.5 while mechanical heat pumps can achieve COPs of 2 or more.
SUMMARYThis Summary is provided to comply with 37 C.F.R. § 1.73, requiring a summary of the invention briefly indicating the nature and substance of the invention. It is submitted with the understanding that it will not be used to interpret or limit the scope or meaning of the claims.
According to a first aspect of the invention, there is provided a solar-thermal system, comprising:
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- a generator component;
- an evaporator component;
- a heat pump ejector comprising a mixing chamber; said heat pump ejector coupled to the generator component and the evaporator component; wherein the generator component emits a vapor stream into said mixing chamber and the heat pump ejector is configured to extract a working fluid vapor from the evaporator component into said mixing chamber through entrainment thereby to form a mixed flow; and
- a condenser component configured to cool said mixed flow via a cooling loop.
According to a second aspect of the invention, there is provided a method for operating a solar-thermal system, comprising:
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- generating a vapor stream in a generator component using heat extracted from a solar thermal collector array;
- feeding said vapor stream into an ejector heat pump comprising a mixing chamber;
- forming a mixed flow in said mixing chamber by extracting a secondary flow into said mixing chamber through entrainment, wherein said secondary flow comprises a working fluid vapor from an evaporator component; and
- condensing said mixed flow in a condenser loop wherein heat is extracted from said mixed flow.
Other aspects and example embodiments are provided in the drawings and the detailed description that follows.
In the following description, for purposes of explanation, numerous specific details are set forth in order to provide a thorough understanding of the invention. It will be apparent, however, to one skilled in the art that the invention can be practiced without these specific details. In other instances, structures and devices are shown in block diagram form only in order to avoid obscuring the invention.
The present invention, in accordance with one or more various embodiments, is described in detail with reference to the following figures. The drawings are provided for purposes of illustration only and merely depict exemplary embodiments of the invention. These drawings are provided to facilitate the reader's understanding of the invention and shall not be considered limiting of the breadth, scope, or applicability of the invention. It should be noted that for clarity and ease of illustration these drawings are not necessarily made to scale
The figures are not intended to be exhaustive or to limit the invention to the precise form disclosed. It should be understood that the invention can be practiced with modification and alteration, and that the invention be limited only by the claims and the equivalents thereof.
DETAILED DESCRIPTIONIn the following description, for purposes of explanation, numerous specific details are set forth in order to provide a thorough understanding of the invention. It will be apparent, however, to one skilled in the art that the invention can be practiced without these specific details. In other instances, structures and devices are shown in block diagram form only in order to avoid obscuring the invention.
Reference in this specification to “one embodiment” or “an embodiment” means that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment of the invention. The appearance of the phrase “in one embodiment” in various places in the specification are not necessarily all referring to the same embodiment, nor are separate or alternative embodiments mutually exclusive of other embodiments. Moreover, various features are described which may be exhibited by some embodiments and not by others. Similarly, various requirements are described which may be requirements for some embodiments but not other embodiments.
Moreover, although the following description contains many specifics for the purposes of illustration, anyone skilled in the art will appreciate that many variations and/or alterations to said details are within the scope of the present invention. Similarly, although many of the features of the present invention are described in terms of each other, or in conjunction with each other, one skilled in the art will appreciate that many of these features can be provided independently of other features. Accordingly, this description of the invention is set forth without any loss of generality to, and without imposing limitations upon, the invention.
The teachings and principles of the present invention are applicable to a wide variety of heating and cooling resources. For purposes of explanation and illustration, however, the present invention is hereafter described in reference to particular embodiments of heating and cooling systems. However, it should be understood, that one of ordinary skill in the art will, upon reference to this description, would be able to apply the principles and teachings of the present invention in a wide variety of such heating and cooling systems.
Referring now to
Over the course of the day the fluid in the thermal storage tank 236 is heated and the stored heat can then be used for some purpose within a residence, a commercial business, or some other useful application that requires heat. Overall the use of the ejector heat pump 210 in the system 200, which comprises the components contained within shaded box 240, enables an increase in the amount of heat which may be collected from the environment by some factor determined by the COP. Thus, for example, if a system without the ejector heat pump is capable of collecting 1 kW of power from the sun, and the COP of the system was 1.3, then the amount of power collected from both the sun and the atmosphere would be 1.3 kW. Advantageously, heat pumps used for conventional air conditioning and cooling have exhibited lifetimes in the field of up to forty years. This makes them very attractive components to be added to a SWH system which has an expected lifetime of 25 years.
Referring again to
Referring now to
Normally rooftop units reject heat from the inside of a building via an air-to-liquid heat exchanger 340 which allows heated fluid (the refrigerant) within the condenser loop to be cooled by interaction with outside air. Coupling the heat exchanger 318 to the condenser loop provides an additional means for extracting heat as the refrigerant experiences additional cooling by being coupled to the evaporator 314 via the heat exchanger 318 and the condenser loop 320, 322. Advantageously, this heat extraction or cooling resource takes some of the burden of the packaged air conditioning unit 324, and thus reduces the electricity required for it to perform the equivalent cooling resource to the building it serves. The overall result is that by using this configuration solar energy may be effectively coupled or retrofitted to an existing air conditioning system in a way which helps to reduce the overall electrical load of the air-conditioning system, thus saving energy and cost. The evaporator 314 may also include or be coupled to a cool thermal storage reservoir. In this way, the cooling resource produced by the ejector heat pump may be accumulated over the course of the day and then applied to reducing the load on the air conditioning system at a time which may be more appropriate, for example when electricity costs are highest. This cool thermal storage reservoir may take the form of an insulated tank of water and or a phase change medium.
Other thermally driven refrigeration cycles may be used in the supplemental cooling and heating applications described above. These include but are not limited to single and multi-effect absorption cycles, adsorption cycles, solid and liquid based desiccant cycles, thermochemical cycles as well as duplex rankine cycles. While these solutions differ in their complexity, cost, and performance, they have the ability to be driven by a heat source of some kind. As such they can find use in these applications if their innate characteristics might somehow make them a more appropriate choice under different circumstances.
Numerous specific details may be set forth herein to provide a thorough understanding of a number of possible embodiments of a digital imaging system incorporating the present disclosure. It will be understood by those skilled in the art, however, that the embodiments may be practiced without these specific details. In other instances, well-known methods, procedures, components and circuits have not been described in detail so as not to obscure the embodiments. It can be appreciated that the specific structural and functional details disclosed herein may be representative and do not necessarily limit the scope of the embodiments.
Although the invention is described above in terms of various exemplary embodiments and implementations, it should be understood that the various features, aspects and functionality described in one or more of the individual embodiments are not limited in their applicability to the particular embodiment with which they are described, but instead can be applied, alone or in various combinations, to one or more of the other embodiments of the invention, whether or not such embodiments are described and whether or not such features are presented as being a part of a described embodiment. Thus, the breadth and scope of the present invention should not be limited by any of the above-described exemplary embodiments.
Terms and phrases used in this document, and variations thereof, unless otherwise expressly stated, should be construed as open ended as opposed to limiting. As examples of the foregoing: the term “including” should be read as meaning “including, without limitation” or the like; the term “example” is used to provide exemplary instances of the item in discussion, not an exhaustive or limiting list thereof; the terms “a” or “an” should be read as meaning “at least one,” “one or more” or the like; and adjectives such as “conventional,” “traditional,” “normal,” “standard,” “known” and terms of similar meaning should not be construed as limiting the item described to a given time period or to an item available as of a given time, but instead should be read to encompass conventional, traditional, normal, or standard technologies that may be available or known now or at any time in the future. Likewise, where this document refers to technologies that would be apparent or known to one of ordinary skill in the art, such technologies encompass those apparent or known to the skilled artisan now or at any time in the future.
The presence of broadening words and phrases such as “one or more,” “at least,” “but not limited to” or other like phrases in some instances shall not be read to mean that the narrower case is intended or required in instances where such broadening phrases may be absent. The use of the term “module” does not imply that the components or functionality described or claimed as part of the module are all configured in a common package. Indeed, any or all of the various components of a module, whether control logic or other components, can be combined in a single package or separately maintained and can further be distributed in multiple groupings or packages or across multiple locations.
Claims
1. A solar-thermal system, comprising:
- a generator component;
- an evaporator component;
- a heat pump ejector comprising a mixing chamber; said heat pump ejector coupled to the generator component and the evaporator component; wherein the generator component emits a vapor stream into said mixing chamber and the heat pump ejector is configured to extract a working fluid vapor from the evaporator component into said mixing chamber through entrainment thereby to form a mixed flow; and
- a condenser component configured to cool said mixed flow via a cooling loop.
2. The solar-thermal system of claim 1, wherein said cooling loop is configured to heat water stored in a thermal storage unit.
3. The system of claim 1, further comprising a solar thermal collector array configured to supply heat to the generator component thereby to facilitate generation of the vapor stream by the generator component.
4. The system of claim 1, wherein the evaporator component extracts heat from outdoor air.
5. The system of claim 1, wherein the evaporator component extracts heat from an air-conditioning unit.
6. The system of claim 1 wherein said generator component, evaporator component, and heat pump ejector are installed on the rooftop of a building.
7. The system of claim 3, wherein said thermal storage unit is installed and ground level.
8. The system of claim 1, wherein said cooling loop comprises a first heat exchanger coupled to said condenser component; and a second heat exchanger configured to extract heat from the solar thermal collector array.
9. A method for operating a solar-thermal system, comprising:
- generating a vapor stream in a generator component using heat extracted from a solar thermal collector array;
- feeding said vapor stream into an ejector heat pump comprising a mixing chamber;
- forming a mixed flow in said mixing chamber by extracting a secondary flow into said mixing chamber through entrainment, wherein said secondary flow comprises a working fluid vapor from an evaporator component; and
- condensing said mixed flow in a condenser loop wherein heat is extracted from said mixed flow.
10. The method of claim 9, wherein said condenser loop comprises a first heat exchanger coupled to a condenser component; and a second heat exchanger configured to extract heat from the solar thermal collector array.
11. The method of claim 10, further comprising pumping water from a thermal storage unit to said first and second heat exchangers thereby to cause said wanted to be heated using the heat extracted from the mixed flow.
12. The method of claim 9, wherein the evaporator component is configured to extract heat from outdoor air.
13. The method of claim 9, wherein the evaporator component is configured to extract heat from an air-conditioning system.
14. The method of claim 10, further comprising locating the thermal storage unit and ground level.
15. The method of claim 10, further comprising locating the generator component, the ejector heat pump, and the evaporator component on the rooftop of a building.
Type: Application
Filed: Feb 19, 2018
Publication Date: Aug 23, 2018
Inventor: Mark W MILES (Oakland, CA)
Application Number: 15/899,286