Patent Application
20240353164
The present disclosure generally relates to an improved apparatus and method of operating a heat pump by reducing or eliminating the need for defrost cycling of the heat pump. More particularly, the present disclosure is directed to an improvement to the operational reliability and overall system capacity and efficiency of a heat pump by using novel means for injecting hot gas discharge from a compressor into the heat-exchange source coil of the heat pump and eliminating the need for defrost cycling of the heat pump.
Conventional heat pumps are widely used in the industry as part of heating and cooling systems for various facilities. A typical heat pump is an electrical device that extracts heat from one place and transfers it to another in order to maintain a constant temperature—primarily by using a refrigerant. A heat pump can be used for both heating and cooling of the facility.
A heat pump transfers heat by circulating the refrigerant through a cycle of evaporation and condensation. In a typical heat pump, a compressor pumps the refrigerant through two heat exchange coils—an outdoor heat exchange/coil (source coil) and an indoor heat exchange/coil (load coil)—in order to exchange and transfer heat between the indoor/outdoor heat exchange coils. The process entails evaporating the refrigerant at low pressure in one of the coils and absorbing heat from its surroundings and compressing the refrigerant as it travels to the other coil and then condensing it at a high pressure. Typically, conventional heat pumps are designed with a four-way reversing valve functioning as a switch between the two primary modes of operation—a cooling mode and a heating mode, as illustrated in
In a conventional heat pump system, an evaporator is generally disposed along an evaporator line, a compressor system disposed along a compressor line, a condenser disposed along a condenser line and configured to condense the refrigerant compressed by the compressor system to heat a second fluid stream, and an outdoor coil disposed along a coil line and configured to receive the refrigerant from the condenser or from a discharge line, to selectively transfer heat to or from the refrigerant, and to selectively transfer the refrigerant to the evaporator or to a suction line. The refrigeration system includes two valves and three expansion valves disposed along the different refrigerant flow lines, and a controller configured to determine a simultaneous heating/cooling operating mode of the refrigeration system.
In addition, as the refrigerant captures more heat and generates higher (warmer) temperatures than the interior/load ambient air during a vapor compression cycle, heat is transferred from the refrigerant into the indoor air of the heat pump. Once the outdoor temperature decreases (generally below 40° F. in a typical heat pump operational environment), moisture in the air forms ice (frost) on the surface of the outdoor heat exchange coil thereby negating any substantial heat transfer within the heat pump and drastically reducing the heat pump performance and efficiency.
In order to counter such degradation of performance and efficiency, conventional heat pumps are designed and configured to run a defrost cycle to eliminate any frost formation. In the defrost mode, the reversing valve of the heat pump activates and runs the refrigerant backwards. A defrost cycle is generally nothing more than the system recognizing ice has formed or is beginning to form and automatically fixing it. However, the process of automatically running the defrost cycle by reversing the heat pump flow of the refrigerant further aggravates performance inefficiencies within a heat pump. For example, during a defrost cycle, first the superheated compressor discharge gas is sent to the outdoor heat exchange/coil (source coil) via a four-way reversing valve. Next, the subcooled refrigerant is sent back from the outdoor heat exchange/coil (source coil) to the indoor heat exchange/coil (load coil) after passing through an expansion or metering device and becoming colder than the indoor ambient temperature and absorbing heat from the air into the refrigerant. An auxiliary or emergency heater (usually electrical resistance or combustion heater) is then energized to compensate for the heat absorbed from the air during the defrost cycle by the indoor heat exchange/coil (load coil).
The decreased heat exchange during the frost buildup, coupled with the use of auxiliary or emergency heaters during the defrost cycle, causes large load temperature swings, loss of operation reliability and lower overall system capacity and efficiency of the heat pump. It is well known within the industry that at a minimum, using auxiliary heat in conventional heat pumps during defrost cycle operations reduces the heat pump's overall performance and/or efficiency from between 10 percent to 20 percent. Therefore, there is a dearth of systems and mechanisms that can remove some of the foregoing disadvantages caused by automatically running the defrost cycle and preventing performance reliabilities while creating inefficiencies within a heat pump. In other words, there is clearly a need within the industry for an improved apparatus and method of operating a heat pump by reducing or eliminating the need for defrost cycling of the heat pump.
The present disclosure is directed to an improvement to the operation, reliability, and overall system capacity and efficiency of a heat pump by using innovative means for injecting hot gas discharge from a compressor into the source coil distributor inlet and eliminating frost buildup on the heat pump.
The present disclosure is directed to an improved system, method and apparatus of heating a space (or a certain volume of air) by reducing or eliminating the need for an automatic defrost cycling of a heat pump.
A no-frost heat pump (heat pump) includes an expansion valve for expanding a liquid refrigerant, a compressor for compressing the refrigerant vapor, a suction accumulator, a first heat exchange coil (functioning as the outside or outside source coil), a second heat exchange coil (functioning as the inside or indoor load coil) and a discharge valve (also known as a discharge gas injection valve)—the various components arranged in a closed loop system for heating a space or a certain volume of air. During operation, the heat pump circulates the refrigerant by pressurizing a liquid refrigerant, heating the liquid refrigerant to form a refrigerant vapor, compressing refrigerant vapor by the compressor, and supplying the heat exchange coils with refrigerant from the compressor—the refrigerant transferring heat by circulating through a cycle of evaporation and condensation, thereby enabling the exchange and transfer of heat between the indoor and outdoor heat exchange coils. During such operation in low outdoor ambient temperatures, the discharge valve-disposed upstream of the first heat exchange coil and fluidly coupled to the first heat exchange coil (source coil) is triggered to inject refrigerant directly into the outdoor heat exchange coil inlet/source coil for preventing the formation of ice/frost on the surface of the coil. Various mechanical (e.g., valves) and/or electrical means (including embedded processors running proprietary algorithms) can be used for controlling the hot gas discharge from the discharge valve of the heat pump. The heat pump disclosed herein improves operational efficiency and performance by eliminating the need for automatic defrost cycling.
In another aspect of the present disclosure, a method of operating the heat pump comprises the steps of: (1) configuring a heat pump with an expansion valve for expanding a liquid refrigerant, a compressor for compressing the refrigerant vapor, a suction accumulator, a first heat exchange coil (functioning as the outside source coil), a second heat exchange coil (functioning as the inside load coil) and a discharge gas injection valve—the various components arranged in a closed loop system for heating a space; (2) circulating the refrigerant through the closed loop system by pressurizing the liquid refrigerant, heating the liquid refrigerant to form a refrigerant vapor, compressing refrigerant vapor by the compressor, and supplying the heat exchange coils with refrigerant from the compressor; (3) exchanging heat between the indoor/outdoor heat exchange coils by circulating the refrigerant through a cycle of evaporation and condensation; and wherein (4) during operation of the heat pump in low outdoor ambient temperatures, the discharge gas injection valve disposed upstream of the first heat exchange coil and fluidly coupled to the first heat exchange coil (source coil) is triggered to inject refrigerant directly into the outdoor heat exchange coil inlet/source coil for preventing the formation of ice/frost on the surface of the coil.
In another aspect of the present disclosure, the heat pump cycle using an expansion valve for expanding the refrigerant fluid and a compressor for the compression of the refrigerant vapor can be used for a wide variety of applications—including using the heat pump cycle for both cooling and heating of a space. For instance, in the cooling mode, such systems pass saturated liquid refrigerant through an expansion valve to lower the refrigerant's pressure, and therefore the saturation temperature of the refrigerant correspondingly falls, and the cooled refrigerant is then directed to an evaporator where heat is absorbed from the atmosphere, thereby cooling the environmental space (or some other medium where cooling is desired). This cycle may be reversed, thus permitting the same system to operate as a heat pump.
Certain embodiments are shown in the drawings. However, it is understood that the present disclosure is not limited to the arrangements and instrumentality shown in the attached drawings.
For the purposes of promoting and understanding the principles disclosed herein, reference is now made to the preferred embodiments illustrated in the drawings, and specific language is used to describe the same. Embodiments disclosed in the present disclosure provide a novel and improved method and apparatus of operating a heat pump by reducing or eliminating the need for automatically running a defrost cycle within a heat pump.
In
The first heat exchange coil 216 functions as the source coil and the second heat exchange coil 220 functions as the load coil for the heat pump 1000 disclosed herein. During operation, the heat pump 1000 circulates the refrigerant by pressurizing a liquid refrigerant, heating the liquid refrigerant to form a refrigerant vapor, compressing refrigerant vapor by the compressor 208, and supplying the heat exchange coil with refrigerant from the compressor—the refrigerant transferring heat by circulating through a cycle of evaporation and condensation, thereby enabling the exchange and transfer of heat between the indoor and outdoor heat exchange coils (216, 220). The source and the load coils (216, 220) work in conjunction to exchange the heat between the indoor and the outdoor heat exchange coils.
As further illustrated in
The heat pump disclosed herein provides substantial performance improvements to the pump's operating range, reliability and longevity. It is to be noted that by eliminating the need for an automatic defrost cycle and the use of auxiliary or emergency heaters during the defrost cycle, the heat pump further prevents large load temperature swings and improves overall system capacity and efficiency of the heat pump. The heat pump can be used for air-to-water heat pump equipment for processing potable hot water generation within the equipment or as a Dedicated Outdoor Air System (DOAS) to artificially load the evaporator coil (load coil) and maintain proper operating suction pressure and temperature while the DOAS is operating at light load conditions.
Apparatus, system and methods disclosed herein can be used for various other equipment including, but not limited to, Process Chillers, Recirculating Heating and Cooling Equipment, HVACs, Hybrid Heat Pumps, Electric Heat Pumps and other similar heating, cooling and ventilation systems.
The use of the terms “a,” “an” and “the” and similar referents in the context of describing the invention (especially in the context of the following claims) is to be construed to cover both the singular and the plural, unless otherwise indicated herein or clearly contradicted by context. The terms “comprising,” “having,” “including” and “containing” are to be construed as open-ended terms (i.e., meaning “including, but not limited to,”) unless otherwise noted. All methods described herein can be performed in any suitable order unless otherwise indicated herein or otherwise clearly contradicted by context. The use of any and all examples, or exemplary language (e.g., “such as”) provided herein, is intended merely to better illuminate the invention and does not pose a limitation on the scope of the invention unless otherwise claimed. No language in the specification should be construed as indicating any non-claimed element as essential to the practice of the invention.
It is understood that the preceding is merely a detailed description of some examples and embodiments of the present disclosure, and that numerous changes to the disclosed embodiments may be made in accordance with the disclosure made herein without departing from the spirit or scope of the disclosure. The preceding description, therefore, is not meant to limit the scope of the disclosure, but to provide sufficient disclosure to allow one of ordinary skill in the art to practice the disclosure without undue burden. The scope of the present disclosure fully encompasses other embodiments that may become obvious to those skilled in the art. Features illustrated or described as part of one embodiment can be used in another embodiment to yield a still further embodiment. Thus, it is intended that the present disclosure cover such modifications and variations as come within the scope of the appended claims and their equivalents. It is to be understood by one of ordinary skill in the art that the present discussion is a description of exemplary embodiments only, and is not intended as limiting the broader aspects of the present disclosure, which broader aspects are embodied in the exemplary constructions.
This application is a continuation of U.S. application Ser. No. 17/684,478, filed Mar. 2, 2022, which claims the benefit of and priority to U.S. Provisional Application No. 63/156,144, filed Mar. 3, 2021, the contents of each of which are hereby incorporated by reference as if fully set forth herein.
| Number | Date | Country | |
|---|---|---|---|
| 63156144 | Mar 2021 | US |
| Number | Date | Country | |
|---|---|---|---|
| Parent | 17684478 | Mar 2022 | US |
| Child | 18762909 | US |
