Abstract: In a refrigeration system having a compressor, a condenser, an evaporator, and a controller for controlling an expansion valve, a process for controlling compressor discharge during a cooling cycle includes monitoring a compressor discharge temperature, operating the expansion valve in a base mode wherein the expansion valve is controlled in response to a difference between actual superheat and desired superheat of the evaporator; and controlling the expansion valve in response to a difference between a set point and a compressor discharge parameter when the ambient air temperature, the return air temperature and the compressor discharge temperature meet respective limits.

Abstract: In a refrigeration system having a compressor, a condenser, an evaporator, and a controller for controlling an expansion valve, a process for controlling compressor discharge during a cooling cycle comprising the steps of monitoring a compressor discharge parameter, comparing the compressor discharge parameter to a set point stored in a controller memory, and selectively operating the expansion valve upstream of the evaporator in response to a difference between the compressor discharge parameter and the set point.

Abstract: A refrigerated transport system includes a prioritizing algorithm to limit the maximum amount of refrigerant flow available to at least one limited cooling compartment by holding a delta T (difference between the supply air temperature and return air temperature) instead of a setpoint temperature in the at least one limited cooling compartment when the available cooling capacity is insufficient to hold a substantially constant temperature in all compartments. A method for creating multiple refrigerated compartment spaces having precision temperature control includes the steps of: prioritizing the compartments by identifying at least one priority compartment to be held at a setpoint temperature; and limiting refrigerant flow to all but the priority compartment when there is insufficient cooling capacity to maintain all compartments at their respective setpoint temperatures.

Abstract: A refrigerated transport system includes a prioritizing algorithm to limit the maximum amount of refrigerant flow available to at least one limited cooling compartment by holding a delta T (difference between the supply air temperature and return air temperature) instead of a setpoint temperature in the at least one limited cooling compartment when the available cooling capacity is insufficient to hold a substantially constant temperature in all compartments. A method for creating multiple refrigerated compartment spaces having precision temperature control includes the steps of: prioritizing the compartments by identifying at least one priority compartment to be held at a setpoint temperature; and limiting refrigerant flow to all but the priority compartment when there is insufficient cooling capacity to maintain all compartments at their respective setpoint temperatures.

Abstract: The accumulation period between defrost cycles of a refrigeration apparatus having a electrical defrost heater is calculated on the basis of energy expended to remove the ice from the coil during the previous defrost cycle. In this way, variations in the voltage level being delivered to the heater coil are taken into account and the degree of ice build-up on the coil between defrost cycles can be more accurately controlled.

Abstract: An improved controlled algorithm for a refrigerant cycle monitors a suction pressure sensor to ensure the suction pressure sensor continues to operate. The controller utilizes a detected suction pressure to assure the suction pressure does not drop below a minimum value, which could result in undesirable conditions within the refrigerant cycle. The controller also monitors the suction pressure sensor signal to ensure the suction pressure sensor is operating properly. If the suction pressure sensor fails, then a control algorithm is utilized wherein a minimum open percentage is set for a suction modulation valve, and the suction modulation valve is not allowed to close beyond the minimum suction modulation valve percentage opening.