Abstract: In a method of operating a compressor at startup, the compressor is rotated in reverse for a brief period of time. The compressor is of a type that does not compress liquid when rotated in reverse. The purpose is to boil off the liquid refrigerant from the oil by heating and agitating the mixture of oil and refrigerant in the oil sump. This results in a much more benign forward start as less refrigerant is drawn into the compressor pump and the amount of oil pumped out of the compressor on start up is minimized. Also, the viscosity of oil is increased and lubrication of the bearings is improved. After a short period of time reverse rotation is stopped and the compressor can start rotating in the forward direction. The short period of time of reverse rotation is varied based upon system conditions. In one embodiment, the variation can occur by reducing the reverse run time as ambient temperature increases.

Abstract: A refrigeration unit for a shipping container exposed to end loads and rack loads. The refrigeration unit has a frame, a back panel, a plurality of structural support brackets secured to the back panel, a condenser cover secured to the plurality of structural support brackets so that the condenser cover, the plurality of structural support brackets, the frame, and the back panel form a structural member sufficient to support end loads and rack loads. The refrigeration unit also has a condenser coil having a first end and a second end, a first coil support member secured to one of the structural support brackets and secured around the first end, and a second coil support member secured to one of the structural support brackets and secured around the second end. The first and second coil support members maintain the condenser coil unstressed from the end loads and rack loads.

Abstract: A refrigerant vapor compression system includes an evaporator having a plurality of longitudinally extending, flattened heat exchange tubes disposed in parallel, spaced relationship. Each of the heat exchange tubes has a flattened cross-section and defining a plurality of discrete, longitudinally extending refrigerant flow passages. One or more frost detection sensor(s) is/are installed in operative association with the evaporator for detecting a presence of frost/ice formation on at one of the flattened heat exchange tubes and associated heat transfer fins. A defrost system is provided and operatively associated with the evaporator heat exchanger A controller, operatively coupled to the frost detection sensor(s) and to the defrost system, selectively activates the defrost system to initiate a defrost cycle of the evaporator in response to the signal indicative of the presence of frost formation on the flattened heat exchange tubes and heat transfer fins.

Abstract: The present disclosure provides a refrigeration unit that can be used in a transport cooling application. The unit comprises a micro-channel heat exchanger (MCHX), a compressor, an evaporator, and a thermostatic expansion valve. The MCHX is coated with an acrylic composition.

Abstract: A control algorithm is developed which takes corrective action in the event that system conditions indicate there may be an inadequate flow of lubricant in the system. In particular, if a discharge pressure is below a predetermined amount or if the suction modulation valve is throttled, there is a possibility of inadequate lubricant flow. The system control then turns off the condenser fan, and if that first step is not sufficient, may also turn on an evaporator heater and then control a suction modulation valve. A fail safe control loop also takes effect if the condition sensor appears to have failed.

Abstract: A method comprises the steps of (a) providing a refrigeration unit having a refrigerated or heated space and at least one measured operating parameter, (b) providing heat to the refrigerated space when the at least one measured operating parameter exceeds a first threshold, (c) terminating provision of heat when the at least one measured operating parameter exceeds a second threshold, and repeating steps b–c when the at least one operating parameter falls below the first threshold. In using this method, the unit can be operated continuously, with substantially higher refrigerant mass flow and evaporator pressure then in the prior art. Higher refrigerant mass flow rate and higher evaporator pressure improve oil return to the compressor, thus reducing the like hood of compressor damage due to oil pump out.

Abstract: A control algorithm is developed which takes corrective action in the event that system conditions indicate there may be an inadequate flow of lubricant in the system. In particular, if a discharge pressure is below a predetermined amount or if the suction modulation valve is throttled, there is a possibility of inadequate lubricant flow. The system control then turns off the condenser fan, and if that first step is not sufficient, may also turn on an evaporator heater and then control a suction modulation valve. A fail safe control loop also takes effect if the condition sensor appears to have failed.

Abstract: A method comprises the steps of (a) providing a refrigeration unit having a refrigerated or heated space and at least one measured operating parameter, (b) providing heat to the refrigerated space when the at least one measured operating parameter exceeds a first threshold, (c) terminating provision of heat when the at least one measured operating parameter exceeds a second threshold, and repeating steps b-c when the at least one operating parameter falls below the first threshold. In using this method, the unit can be operated continuously, with substantially higher refrigerant mass flow and evaporator pressure then in the prior art. Higher refrigerant mass flow rate and higher evaporator pressure improve oil return to the compressor, thus reducing the like hood of compressor damage due to oil pump out.