A device under test cooling system has a refrigerant line and a fluid line extending through a plurality of successively arranged heat exchangers. A digital scroll compressor has an intake for providing the refrigerant mixture to the compressor and a discharge connecting the compressor to the refrigerant line to provide the refrigerant mixture to the heat exchangers. The compressor includes a plurality of scroll elements between the intake and the discharge for compressing the refrigerant mixture. The compressor includes a valve configured to separate the scroll elements when in an open position to allow refrigerant to flow freely between the intake and the discharge. When the valve is in a closed position, the scroll elements compress the refrigerant. A controller is configured to switch the valve between an open and closed position based on a set duty cycle.

An air-conditioning device includes (i) a compressor, (ii) an outdoor heat exchanger, (iii) an indoor heat exchanger and an electronic expansion valve, (iv) a bypass passage connecting a middle compression chamber and a low pressure space, the middle compression chamber accommodating a refrigerant undergoing compression by the compressor, the low pressure space accommodating the refrigerant having a pressure lower than a pressure of the refrigerant in the middle compression chamber, (v) a bypass valve to open or close the bypass passage, and (vi) a controller to set a degree of opening of the electronic expansion valve based on a degree of superheat of a refrigerant. Based on a change from a closed state of the bypass valve to an open state, the controller corrects the degree of opening of the electronic expansion valve to a value that is less than a value set by the degree-of-superheat control.

A control system for controlling an output for at least one compressor includes a control unit that receives an indoor set point and an outdoor ambient temperature. The control unit determines a load request based on the indoor set point and the outdoor ambient temperature without considering an indoor room temperature. The at least one compressor receives control commands from the control unit based on the load request.

A screw compressor, method of operating, and refrigerant circuit are disclosed. The screw compressor includes a suction inlet that receives a working fluid to be compressed. A compression mechanism is fluidly connected to the suction inlet that compresses the working fluid. A discharge outlet is fluidly connected to the compression mechanism that outputs the working fluid following compression by the compression mechanism. A valve assembly is configured to vary a location at which the compression mechanism compresses the working fluid, the valve assembly being disposed to modify a suction location of the screw compressor.

For creating a storage unit comprising a container housing enclosing a storage volume for receiving freight and a gaseous medium surrounding said freight, said storage unit further comprising a tempering system provided with a tempering unit associated with said storage volume for maintaining a flow of said gaseous medium circulating in said storage volume and passing through said tempering unit in order to be maintained at a defined or set temperature, said tempering unit comprising an internal heat exchanger arranged in said flow of gaseous medium passing through said tempering unit, said tempering system being provided with a refrigerant circuit comprising said internal heat exchanger, an external heat exchanger exposed to ambient air surrounding said container housing which operates reliably and cost efficient under the aforementioned condition, as well as a compressor unit for compressing refrigerant, and said tempering system being further provided with an engine for driving said compressor unit in an independent power source mode and said tempering system being further provided with an electric motor/generator unit mechanically coupled to said compressor unit, and said compressor unit and said motor/generator unit being commonly driven by said engine in said independent power source mode.

Methods and systems for controlling a chiller system to achieve control stability while maintaining optimum efficiency. Particularly, methods and systems for controlling a centrifugal compressor speed and an inlet guide vane position that establishes three distinct regions in the control path: (i) during initial unloading from full load, the inlet guide vane position is kept at a fully open position while the centrifugal compressor speed is changed to achieve the desired cooling capacity; (ii) between an inflection point and a transition point, keeping the centrifugal compressor speed constant while the inlet guide vane position is changed to achieve the desired cooling capacity; and (iii) between the transition point and zero cooling capacity, changing both the inlet guide vane position and the centrifugal compressor speed to achieve the desired cooling capacity.

Systems and methods for compressor unloading detection are provided and include a compressor having a compression mechanism. A controller determines a predicted discharge temperature of the compressor, receives an actual discharge temperature of the compressor, and compares the predicted discharge temperature with the actual discharge temperature. The controller also compares a speed of the compressor with a speed threshold and detects unloading of the compression mechanism based on the comparison of the predicted discharge temperature with the actual discharge temperature and based on the comparison of the speed of the compressor with the speed threshold. The controller performs at least one of generating an alert and a remediating action in response to detecting the unloading of the compression mechanism.

A scroll compressor is disclosed. The scroll compressor includes a compressor housing; an orbiting scroll member disposed within the housing; a non-orbiting scroll member disposed within the housing, wherein the orbiting scroll member and the non-orbiting scroll member are intermeshed thereby forming a compression chamber within the housing; and an endplate secured to the non-orbiting scroll member. The endplate includes a check valve surface configured to provide a stop for a check valve of the scroll compressor, a radial sealing surface configured to receive a radial seal, an unloading mechanism surface configured to provide a stop for an unloading mechanism, and a pressure chamber for controlling the unloading mechanism, the endplate also including an aperture that fluidly connects the compression chamber and a discharge chamber of the scroll compressor.

An intermediate discharge port in a scroll compressor and a method for controlling part-load efficiency of a scroll compressor are disclosed. The compressor includes a compressor housing; a non-orbiting scroll member and an orbiting scroll member forming a compression chamber; a discharge port for receiving a compressed fluid; and an intermediate discharge port fluidly connected between the compression chamber and the discharge port, the intermediate discharge port including a sealing member, fluid flow being prevented between the compression chamber and the discharge port through the intermediate discharge port when in a flow-blocked state, and fluid flow being enabled between the compression chamber and the discharge port through the intermediate discharge port when in a flow-permitted state.

A variable-capacity compressor that includes a housing having an inlet for receipt of refrigerant and an outlet for return of refrigerant, and a plurality of compressing elements contained in the housing between the inlet and the outlet. The variable capacity compressor includes a valve having an electrical control. The valve is dedicated to fewer than all of the compressing elements. The valve is movable between a first state which communicates refrigerant flow to the compressing elements, and a second state that reduces or stops flow to the compressing elements. In an embodiment of the invention, an unloading controller has an operational modulation mode that includes cycling the valve between on and off states to provide a portion of compressor capacity. The unloading controller is further programmed to provide a minimum delay time between transitions between the first and second states, but no maximum dwell time between transitions.