Abstract: The present invention relates to a way of reducing the amount of energy required to partially compress a refrigerant in a compressor operating in a rapidly cycled unloaded mode. A valve on a suction line is closed when the compressor moves to the unloaded condition. In this manner, the amount of energy required to partially compress the refrigerant in the compressor, at the unloaded condition, is dramatically reduced.

Abstract: A refrigerant system is provided with a pulse width modulation valve. A compressor temperature is monitored to prevent potential reliability problems and compressor failures due to an excessive temperature inside the compressor. A control changes the pulse width modulation valve duty cycle rate to maintain temperature within specified limits, while achieving the desired capacity, and complying with design requirements of a conditioned environment, without compromising refrigerant system reliability. As the compressor temperature increases, the pulse width modulation valve duty cycle time is adjusted to ensure that adequate amount of refrigerant is circulated through the compressor to cool the compressor internal components.

Abstract: A fuel-powered engine is provided to drive a mobile air conditioning or refrigeration unit such as a portable chiller, a container refrigeration unit, a portable packaged system, a transport tractor-trailer or truck refrigeration unit, etc. A control rapidly changes the engine speed between the predefined set of discreet engine speeds to precisely adjust the capacity of the refrigerant system. If the engine operates only at a single speed, then the control cycles the engine between this operating speed and a zero speed (the engine is shut off). If the engine can operate at multiple discreet speeds, then the control can cycle the engine between any of these speeds (including a zero speed). When a lower capacity is desirable, the engine operates for a longer time interval at a lower speed, and when a higher capacity is desirable, the engine operates for a longer period of time at a higher speed. The cycle rate is selected to control the comfort (e.g.

Abstract: A parallel flow heat exchanger system (10, 50, 100, 200) for heat pump applications in which single and multiple paths of variable length are established via flow control systems which also allow for refrigerant flow reversal within the parallel flow heat exchanger system (10, 50, 100, 200), while switching between cooling and heating modes of operation. Examples of flow control devices are an expansion device (80) and various check valves (70, 72, 74, 76). The parallel flow heat exchanger system may have converging or diverging flow circuits and may constitute a single-pass or a multi-pass evaporator together with and a multi-pass condenser.

Abstract: A reciprocating compressor includes a first cylinder and a second cylinder, first and second suction cutoff unloader valve assemblies, and a controller. The first and second suction cutoff unloader valve assemblies are integral to the compressor and are capable of a rapid cycling to interrupt flow of refrigerant to the first and second cylinders. The controller operates at least one of the first suction cutoff unloader valve assembly or second suction cut-off unloader valve assembly in the rapid cycling and monitor a number of rapid cycles. In another aspect, a multi-stage compressor comprises a lower pressure stage and a higher pressure stage, and at least one suction cutoff unloader valve assembly capable of a rapid cycling to interrupt flow of refrigerant to a lower stage cylinder.

Abstract: A refrigerant system includes at least one compressor (54, 56) that compresses refrigerant and delivers it downstream to a heat rejection heat exchanger (26). The heat rejection heat exchanger is a microchannel heat exchanger. Refrigerant passes from the heat rejection heat exchanger downstream to an expansion device (60), from the expansion device through an evaporator (66), and from the evaporator back to the at least one compressor. A control (58) operates at least one compressor and the expansion device to reduce pressure spikes at transient conditions.

Abstract: A reciprocating compressor includes a cylinder block, a cylinder head, and a bypass unloader valve assembly. The cylinder block has a cylinder disposed therein. The cylinder head is secured to the cylinder block overlying the cylinder and has a suction plenum and a discharge plenum in selective fluid communication with the cylinder. The bypass unloader valve assembly is in operable communication with the cylinder head and is responsive to control signals to rapid cycle to allow for fluid communication of a refrigerant between the discharge plenum and the suction plenum.

Abstract: A refrigerant system capable of operating at multiple capacity modes includes an evaporator, a multi-stage compressor assembly, a first fluid flow path, a second fluid flow path, a first valve, and a second valve. The multi-stage compressor assembly has a first stage and a second stage. The first fluid flow path extends from the evaporator to the first stage of the multi-stage compressor assembly. The second fluid flow path connects to the first fluid flow path and to the multi-stage compressor assembly between the first stage and the second stage.

Abstract: A refrigerant system is provided with an expansion device that may be a thermostatic expansion device or an electronic expansion device. A bypass line selectively allows a portion of refrigerant to bypass the expansion device and to flow through a fixed restriction expansion device such as an orifice positioned in parallel configuration with the main expansion device. A valve selectively enables or blocks refrigerant flow through this bypass line depending on the volume of refrigerant required to circulate through the refrigerant system as defined by environmental conditions and a mode of operation. The valve can be a simple shutoff valve or a three-way valve selectively allowing or blocking refrigerant flow through a particular refrigerant line or lines. In one embodiment, the expansion device is the main expansion device for the refrigerant system. In the other embodiment, the expansion device is a vapor injection expansion device for expanding refrigerant for performing an economizer function.

Abstract: A multi-zone HVAC&R system has its control programmed to provide diagnostic testing of air handling components and refrigerant components associated with each climate controlled zone in sequence. The control changes the original position of the corresponding component and a resultant change in a relevant operational parameter is sensed. If the actual change is outside of the tolerance band associated with the expected change, then the determination is made that the component under consideration is malfunctioning. The periodicity of a diagnostic procedure for a particular component is typically defined by its criticality and reliability level. If the change in the corresponding operation parameter is recorded and stored in the database, the component degradation can be observed over time and a prognostic prediction can be made when a particular component requires preventive maintenance or replacement.

Abstract: A refrigerant system includes a compressor that has safe operating limits that are also built into a refrigerant system control to protect the compressor. Under certain conditions, these safe operational limits may be changed to allow the compressor to operate beyond the safety limits at least for a period of time.

Abstract: A refrigerant vapor compression system includes a hot gas bypass line establishing refrigerant vapor flow communication between the compression device and the refrigerant heat absorption heat exchanger, and bypassing the refrigerant heat rejection heat exchanger and the primary expansion device. A refrigerant vapor flow control device is interdisposed in the hot gas bypass line. The flow control device has at least a first open position in which refrigerant vapor flow may pass through the hot gas bypass line and a closed position in which refrigerant vapor flow may not pass through the hot gas bypass line.

Abstract: A refrigerant system (10, 100, 200) is provided with a power control system (30, 130, 230). The power control system adjusts the speed of the motors driving the refrigerant system components such as a compressor, a fan or a pump via a variable speed device (75, 175, 275) or bypasses the variable speed device (75, 175, 275) for normal operating speeds. A single power control system may be provided for the entire refrigerant system or each component may be independently controlled.

Abstract: A refrigerant system operates with tandem compressors. As is known, one or more of the tandem compressors can be shut down at part-load operating conditions when lower refrigerant system capacity is required. A control periodically engages at least one shut down tandem compressor for a short period of time. This increases the refrigerant mass flow of refrigerant throughout the refrigerant system to ensure that oil travels through the system and is not retained in the system.

Abstract: A scroll compressor is provided with a multiple-speed motor. A control selects a speed for operating the motor, along with selecting between several available options for the system capacity adjustment to meet external load demands in a most efficient and reliable manner. The disclosed embodiment includes an economizer circuit, an unloader function, and an optional suction modulation valve. By utilizing each of these features in combination with the multi-speed motor for the compressor, the present invention is better able to tailor provided capacity to desired capacity.

Abstract: An economized refrigerant vapor compression system (10) for water heating includes a refrigerant compression device (20), a refrigerant-to-water heat exchanger (30), an economizer heat exchanger (60), an evaporator (40) and a refrigerant circuit (70) providing a first flow path (OA, 70B, 70C, 70D) connecting the compression device (20), the refrigerant-to-liquid heat exchanger (30), the economizer heat exchanger (60) and the evaporator (40) in refrigerant circulation flow communication and a second flow path (70E) connecting the first flow path (62) through the economizer heat exchanger (60) to the compression device (20). The economizer heat exchanger (60) has a first pass (62) for receiving a first portion of the refrigerant having traversed the refrigerant-to-liquid heat exchanger and a second pass (64) for receiving a second portion of the refrigerant having traversed the refrigerant-to-liquid heat exchanger.

Abstract: A refrigerant system has at least one unloader valve selectively communicating refrigerant between the compressor compression chambers and a point upstream of the evaporator. When the compressor is run in unloaded mode, partially compressed refrigerant is returned to a point upstream of the evaporator. In an unloaded mode, a higher refrigerant mass flow rate passes through the evaporator, as compared to prior art where the by-passed refrigerant was returned downstream of the evaporator. This increases system efficiency by more effectively returning oil which otherwise might be left in the evaporator back to the compressor. Also, the amount of refrigerant superheat entering the compressor in unloaded operation is reduced as compared to the prior art compressor systems, wherein the by-passed refrigerant is returned directly to the compressor suction line. Reduced refrigerant superheat increases system efficiency, improves motor performance and reduces compressor discharge temperature.

Abstract: A multi-rotor screw compressor includes a housing, a sun rotor, and first and second planet rotors. The first planet rotor intermeshes with the sun rotor to define a first compression pair. The second planet rotor intermeshes with the sun rotor to define a second compression pair. The first and second compression pairs are rotatably mounted in the housing. The housing includes a first port, a portion of which is in communication with the first compression pair, and a second port, a portion of which is in communication with the second compression pair. The portions of the first and second ports which communicate with the first and second compression pairs have a different geometry for offsetting pulsations in a working fluid flowing through the ports.

Abstract: A refrigerant system having tandem compressors includes at least two compressors of different types. By utilizing the two distinct compressor types, a greater difference in the provided capacity of the two compressors can be achieved at part-load conditions, as well as a particular compressor type can be engaged at specific environmental conditions to provide the most efficient operation of the refrigerant system.

Abstract: A refrigerant cycle is disclosed having a number of compressors operating in tandem and supplying a compressed refrigerant to a refrigerant system. Discharge lines communicate a compressed refrigerant to a central discharge line for receiving flow from all tandem compressors. A control is operational to determine a number of compressors need to be operated or whether some compressors should be shutdown to satisfy load requirements. Shutoff valves are placed on discharge lines outwardly of the shell of the compressors. That can be shutdown during part load operation. These shutoff valves are closed when their associated compressors are stopped to prevent backflow of refrigerant from operating compressors through the shutoff compressor, and into the system suction side. Additionally, high pressure differential across the compressor internal discharge check valve is eliminated and the possibility of compressor flooding through a discharge line is reduced.