Abstract: A refrigerant system utilizes an expander to expand refrigerant and to drive or assist in driving an associated compressor. By varying the compressor load, the speed of the expander can be adjusted to achieve the desired thermodynamic characteristics of the expanding refrigerant and enhance expander operation.

Abstract: A heating system includes a refrigerant boiler including a heat source for heating a refrigerant from a liquid state to a vapor state, a boiler outlet and a boiler inlet; a heat exchanger in fluid communication with the refrigerant boiler, the heat exchanger including a upper manifold having a heat exchanger inlet coupled to the boiler outlet, a lower manifold having a heat exchanger outlet coupled to the boiler inlet and a plurality of tubes connecting the upper manifold and the lower manifold, wherein refrigerant passes from the upper manifold to the lower manifold via gravity; and a fan moving air over the heat exchanger to define supply air for a space to be heated.

Abstract: A multiple tube bank heat exchanger includes a first tube bank (100) including at least a first and a second flattened tube segments extending longitudinally in spaced parallel relationship and a second tube bank (200) including at least a first and a second flattened tube segments extending longitudinally in spaced parallel relationship. The second tube bank (200) is disposed behind the first tube bank (100) with a leading edge of the second tube bank spaced from a trailing edge of the first tube bank. A continuous folded plate fin extends between the first and second flattened tube segments of both of said first tube bank and said second tube bank.

Abstract: A transport refrigeration unit is provided which having a refrigerant heat rejection heat exchanger (condenser/gas cooler) that promotes adequate water drainage and corrosion durability. A wraparound finned tube coil has a plurality of heat exchange tube loops and a plurality of plate fins mounted to the plurality of heat exchange tube loops. Each heat exchange tube loop is formed by a plurality of linear tube segments or hairpin tube segments connected by return bends, with each linear tube segment or hairpin segment extending longitudinally at an inclination angle with respect to vertical of at least 20 degrees.

Abstract: Adequate distribution of a two-phase refrigerant flowing through a plurality of heat transfer tubes in a generally parallel manner is ensured. Tapping a portion of predominantly vapor refrigerant from an upstream location and delivering it to a downstream location where separation of liquid and vapor refrigerant phases is likely to occur and a liquid refrigerant phase is likely to accumulate. Additional momentum from the predominantly vapor refrigerant creates homogeneous conditions for the vapor/liquid refrigerant mixture, promoting uniform distribution of the mixture In downstream heat transfer tubes. The vapor refrigerant may be tapped from various locations.

Abstract: A refrigerant vapor compression system includes a compression device, a heat rejecting heat exchanger, an economizer heat exchanger, an expander and an evaporator disposed in a refrigerant circuit. An evaporator bypass line is provided for passing a portion of the refrigerant flow from the main refrigerant circuit after having traversed a first pass of the economizer heat exchanger through the expander to partially expand it to an intermediate pressure and thence through a second pass of the economizer heat exchanger and into an intermediate pressure stage of the compression device. An economizer bypass line is also provided for passing a portion of the refrigerant from the main refrigerant circuit after having traversed the heat rejecting heat exchanger through a restrictor type expansion device and thence into the evaporator bypass line as liquid refrigerant or a mix of liquid and vapor refrigerant for injection into an intermediate pressure stage of the compression device.

Abstract: A heat exchanger includes a plurality of tubes (12), each tube configured for a flow of fluid therethrough and one or more fins located between adjacent tubes of the plurality of tubes. The one or more fins are spaced by a fin pitch (Fp,18) and are configured to improve thermal energy transfer between the plurality of tubes and ambient air. Each fin includes a fin face extending between the adjacent tubes, a substantially planar fin cap (22) connected to the fin face secured to one or the tubes, and a fin radius (Rc,26) connecting the fin face to the fin cap such that the fin radius is reduced to promote condensate removal from the heat exchanger.

Abstract: A heat exchanger (10) is provided including at least one aluminum alloy tube (12) and a plurality of aluminum fins (26) arrayed on the aluminum alloy tube. The aluminum tube may be supported by tube sheets (24) made of aluminum alloy.

Abstract: A refrigerant system is provided with a suction pulse width modulation valve, and a pulse width modulation control for controlling this valve. System pressures, such as the pressure on the evaporator and the condenser are monitored. The measured system pressures are maintained within a band of acceptable lower and upper limits. As the pulse width modulation control cycles the valve, the refrigerant pressures in the evaporator and the condenser tend to fluctuate. The control ensures those fluctuations are within the limits by controlling the duty cycle of the valve.

Abstract: Refrigerant systems are provided with selectively operable components that allow variation in the capacity provided by the refrigerant system to achieve desired temperature and humidity levels. A reheat circuit is provided and an economizer circuit may also be added to the system. Typically, the reheat and economizer functions each provide a step change in the humidity control. A compressor having a variable speed drive is utilized. By providing the reheat/economizer functions along with the variable speed compressor, continuously adjustable humidity control is achieved.

Abstract: A heat pump refrigerant system is provided with at least two sequential stages of compression. An intercooler is positioned intermediate the two stages. The refrigerant flowing through the intercooler. is cooled by a secondary fluid such as ambient air. The intercooler is positioned to be in a path of air flow passing over an outdoor heat exchanger, and preferably upstream of the outdoor heat exchanger, in relation to this air flow. Benefits with regard to efficiency and capacity are achieved due to proposed system configuration in both heating and cooling modes of operation, while no additional circuitry or components are required to provide the intercooler function for the heat pump refrigerant system. This invention is particularly important for the CO2 heat pump refrigerant systems operating in the transcritical cycle.

Abstract: A refrigerant system is provided with at least two sequential stages of compression. An intercooler is positioned intermediate the two stages. The refrigerant flowing through the intercooler is cooled by a secondary fluid such as ambient air. A vapor/liquid injection function is also provided for the refrigerant system. The intercooler function and the vapor/liquid injection function are selectively activated on demand depending on environmental conditions and thermal load in a conditioned space. This invention is particularly important for the CO2 refrigerant systems operating in the transcritical cycle.

Abstract: A refrigerant system is provided that includes a compressor, a motor for driving the compressor, a refrigerant system component, and a controller. The refrigerant system component can operate in a pulse width modulated mode having a loaded phase and an unloaded phase. The compressor motor is loaded in the loaded phase but unloaded in the unloaded phase. The controller applies a first voltage to the compressor motor in the loaded phase and a second voltage to the compressor motor in the unloaded phase. Here, the second voltage is less than the first voltage.

Abstract: A fuel cell is provided to furnish electrical power to an HVAC&R system, and the waste heat from the fuel cell is transferred to a secondary fluid directed to flow to the climate-controlled space of a building during periods of time in which heating is required. The heat rejected by the fuel cell may be a supplemental or primary source of heat as well used for precise temperature control within the climate-controlled space of the building. A channeling assembly is used to selectively direct the fuel cell heat either to and/or away from the climate-controlled space served by the HVAC&R system. Higher energy efficiencies of the HVAC&R equipment are achieved, and the “cold blow” phenomenon is reduced or eliminated.

Abstract: To address the problem of lubricant entrainment within the refrigerant system components such as an evaporator and suction line, a control is provided to periodically, substantially and intermittently increase the refrigerant flow through these components to thereby carry the trapped lubricant back to the compressor. The increased flow of refrigerant can be accomplished by periodically throttling and then unthrottling either an expansion device or a suction modulation valve to cause instantaneous pressure buildup within a respective section of the vapor compression system and subsequent increase of the refrigerant flow through the above-referenced components such as an evaporator and suction line. Suggested time intervals of both the throttling and unthrottling states are provided, as well as the frequency of occurrence for subsequent oil return cycles.

Abstract: A refrigerant system is provided with at least two stages of compression connected in series. An intercooler is positioned intermediate the two stages and is cooled by an indoor air stream. The intercooler is positioned to be in a path of air flow passing over an indoor heat exchanger, and preferably downstream of the indoor heat exchanger, in relation to this airflow. The intercooler cools the refrigerant flowing between the two compression stages as well as provides the reheat function. Benefits with regard to system performance (efficiency, capacity and reliability) are achieved with no additional circuitry or components required to provide the intercooler and reheat functions. This invention is particularly important for the CO2 refrigerant systems operating in the transcritical cycle. Methods of control are presented for both the intercooler and reheat functions.

Abstract: A refrigerant system incorporates an expander. At least a portion of refrigerant bypasses an evaporator and is injected into the compression process to cool main refrigerant vapor flow and compressor elements. In disclosed embodiments, the injected refrigerant may be partially expanded in the expander and routed either into the compressor suction or to an intermediate point in the compression process. A valve may control the amount of the injected refrigerant to achieve desired operational characteristics for the refrigerant system.

Abstract: Various control methods are disclosed for removing moisture from the external surfaces of an evaporator in a refrigerant system to avoid moisture entering a conditioned space. In one embodiment, the evaporator fan is driven in a reverse direction, and the air is guided to the outdoor environment. In other embodiments, a supplemental exhaust fan is utilized in conjunction with the evaporator fan. Also, a reheat circuit, hot gas bypass circuit, or specific features of a heat pump unit may be utilized to more efficiently perform the moisture removal.

Abstract: A compressor assembly includes at least two tandem compressors. Tandem compressors have at least one common suction manifold, communicating a source of working fluid to be compressed by each of at least two compressors, and at least one common discharge manifold communicating a compressed fluid downstream for further use. A common intermediate pressure manifold communicates with intermediate pressure ports in at least two compressors. The intermediate manifold may communicate fluid to or out of the at least two compressors. There is normally no direct communication between suction and discharge manifolds.

Abstract: A parallel flow heat exchanger is disclosed having heat transfer tubes with a plurality of relatively small channels, which are aligned in a parallel manner, and wherein the heat transfer tubes are in fluid communication with at least one manifold structure, are received in manifold wall openings and are attached to the manifold structure by brazing process The manifold walls and/or the tubes are modified to minimize the likelihood of brazing material plugging or at least partially blocking any of the plurality of channels In one feature, the openings in the manifold structure are formed by deforming the material of the manifold structure outwardly In another feature, the edges of the heat transfer tubes may be formed such that the outermost end channels within each heat transfer tube extend farther inwardly than do the central channels Various design configurations are disclosed.