A method of defrost operation optimization in a heat pump includes launching a heating mode after completion of a performed defrost operation, measuring, after launching the heating mode, a heat transfer capability, determining if the measured heat transfer capability is less than or equal to a predetermined heat transfer capability limit for a non-iced condition, and reinforcing a next defrost operation if the measured heat transfer capability is greater than the predetermined gap limit.

A control device controls a heating capacity during a heating operation and a defrosting capacity during a defrosting operation. The defrosting capacity of the first refrigeration cycle unit is determined to fall within a range satisfying a first determination condition and within a range satisfying a second determination condition. The first determination condition is a condition that a sum of a load capacity of a load device when the first defrosting start condition is satisfied, and the defrosting capacity of the first refrigeration cycle unit does not exceed the heating capacity of a second refrigeration cycle unit. The second determination condition is a condition that a sum of an inter-unit defrosting interval and a defrosting period of the first refrigeration cycle unit does not exceed a shortest defrosting interval of the second refrigeration cycle unit.

A refrigeration system includes a receiver, a gas bypass valve, a parallel compressor, and a controller. The gas bypass valve and the parallel compressor are fluidly coupled to an outlet of the receiver in parallel and configured to control a pressure of a gas refrigerant in the receiver. The controller is configured to switch from operating the gas bypass valve to operating the parallel compressor to control the pressure of the gas refrigerant in the receiver in response to a value of a process variable crossing a switchover setpoint. The value of the process variable depends on an amount of the gas refrigerant produced by the refrigeration system. The controller is configured to automatically adjust the switchover setpoint in response to the amount of the gas refrigerant produced by the refrigeration system being insufficient to sustain operation of the parallel compressor.

A system for starting a refrigeration system includes a liquid line regulating valve, a liquid line charging valve, a suction line expansion valve, a suction line charging valve, and a controller. The controller is configured to override normal operation of the refrigeration system and transmit a demand signal to enable partial system operation. The controller is configured to operate the liquid line regulating valve and the liquid line charging valve to charge a receiver tank, gradually increase the demand signal to a predetermined level of partial system operation, and release the liquid line charging valve to normal operation. The controller is configured to operate the suction line expansion valve and the suction line charging valve to charge a suction line, gradually increase the demand signal to full system operation, and release the liquid line regulating valve, the suction line expansion valve, and the suction line charging valve to normal operation.

The refrigeration cycle apparatus includes: liquid-side connection piping that extends from liquid-side refrigerant piping; gas-side connection piping that extends from gas-side refrigerant piping; a refrigerant storage tank that stores refrigerant, an intake side thereof being connected to the liquid-side connection piping, and a discharge side thereof being connected to the gas-side connection piping; an inlet-side electromagnetic valve that is disposed on the liquid-side connection piping, and that is opened when there is no passage of electric current; an inlet-side check valve that is disposed on the liquid-side connection piping, and that allows the refrigerant to flow only toward the refrigerant storage tank; and a valve apparatus that is disposed on the gas-side connection piping, that is opened during passage of electric current to the inlet-side electromagnetic valve, and that is delayed before being shut off after passage of electric current to the inlet-side electromagnetic valve is stopped.

The present disclosure relates to a method for controlling a level of superheat during a pump mode of operation of a refrigeration system, wherein the refrigeration system can operate in either the pump mode or a compressor mode, and has an electronically controlled expansion valve (EEV). A controller obtains a stored, predetermined pump differential pressure range able to be produced by a pump of the system. The controller also obtains a stored, predetermined superheat range, and detects a superheat level. When the detected superheat level is outside of the superheat temperature range, the controller commands adjusting at least one of the EEV and a speed of the pump based on whether the detected superheat level is above or below the superheat range, and whether a current pump differential pressure is above or below the predetermined pump differential pressure range.

A climate-control system may include a compressor and a control module. The compressor includes a motor driving a compression mechanism to compress a working fluid. The control module is in communication with the motor and may be configured to determine a balance speed of the motor at which a forward-rotational inertial force of the compression mechanism is equal to a backward-rotational gas force on the compression mechanism. The control module may be configured to adjust a running speed of the motor to the balance speed after receipt of a compressor-shutdown-command and before shutting down the compressor.

Embodiments of the present disclosure relate to refrigerators and methods of controlling the refrigerators. The refrigerator comprises a compressor configured to operate at a first rotation speed and a controller configured to calculate a first average of levels of electric signals input to the compressor during a first reference period, and control the compressor to operate at a second rotation speed higher than the first rotation speed when the first average is greater than a first reference value.

A multi-split system and a medium-pressure controlling method thereof are provided. The multi-split system includes an outdoor unit, a distribution device, and a plurality of indoor units. The distribution device includes a gas-liquid separator, a first heat exchange assembly, a first electronic expansion valve, a second heat exchange assembly and a second electronic expansion valve. The distribution device is configured to perform a routine correction on a medium-pressure control target value of the first electronic expansion valve according to the subcooling degree of the heating indoor unit, the outlet air temperature of the heating indoor unit and the opening of the throttling element in the heating indoor unit, and to correct a current medium-pressure control target value of the first electronic expansion valve according to a preset step when the opening of the throttling element reaches a maximum opening or a minimum opening and lasts for a first preset time.

A method of refrigeration control through a refrigeration system of a refrigerated transport container includes performing a defrost cycle on the refrigeration system by activating a heat source; and restarting the refrigeration system after the defrost cycle has completed, wherein restarting the refrigeration system includes performing a liquid slugging avoidance process including: initiating a compressor of the refrigeration system at a speed; opening a pressure equalization valve in parallel with the compressor in response to the initiating; opening a liquid valve in series between a condenser and an evaporator after opening of the pressure equalization valve; and closing the pressure equalization valve after a period of time.