A climate-control system may include a compressor, a condenser, an evaporator, a first sensor, a second sensor, a third sensor, and a control module. The compressor may include a motor and a compression mechanism. The condenser receives compressed working fluid from the compressor. The evaporator is in fluid communication with the compressor and disposed downstream of the condenser and upstream of the compressor. The first sensor may detect an electrical operating parameter of the motor. The second sensor may detect a discharge temperature of working fluid discharged by the compression mechanism. The third sensor may detect a suction temperature of working fluid between the evaporator and the compression mechanism. The control module is in communication with the first, second and third sensors and may determine whether a refrigerant floodback condition is occurring in the compressor based on data received from the first, second and third sensors.

A temperature control system according to one embodiment includes: a refrigeration apparatus in which a compressor, a condenser, an expansion valve and an evaporator are connected in this order for circulating a refrigerant; a fluid circulation apparatus that causes a fluid to be heat-exchanged in the evaporator, then sends the fluid to a temperature control object, and again causes the fluid having passed through the temperature control object to be heat-exchanged in the evaporator, the fluid circulation apparatus having a heater at a position downstream of the temperature control object and upstream of the evaporator; and a control apparatus. The control apparatus activates the heater to heat the fluid by the heater, when the fluid circulation apparatus has become in a no-load operation state or a no-load-operation transition operation state, wherein the no-load operation state is a state in which the fluid and the temperature control object do not heat-exchange, the no-load-operation transition operation state is a state that is in transition to the no-load operation state.

Unique apparatuses, methods, and systems of opposing, limiting, and/or preventing undesired or un-commanded compressor rotation are disclosed. One exemplary embodiment is an HVACR system comprising a variable frequency drive configured to drive an electric motor to rotate a screw compressor or scroll compressor. A controller is configured to monitor various aspects of the system and to control the drive. When a condition indicative of potential undesired or un-commanded compressor rotation is identified, the controller commands the variable frequency drive to control the motor to limit and preferably prevent compressor rotation. One technique comprises shorting switches of the drive to a DC bus rail to allow back EMF induced current in the motor windings to be dissipated through winding resistance thus providing a damping force. Another technique comprises controlling the inverter to insert a DC current into the motor to cause the motor to align to and hold a particular position.

Stress to be imposed on a compressor in reverse cycle operation is reduced. A cycle controller causes an outdoor heat exchanger to function as a condenser and an indoor heat exchanger to function as an evaporator when a reverse cycle executing condition is met, so that a refrigerant circulates in reverse of a heating cycle. A rotation speed controller adjusts a rotation speed of a compressor in a reverse cycle, depending on an index correlated with an amount of frost on the outdoor heat exchanger at a start of the reverse cycle. The rotation speed controller decreases the rotation speed of the compressor in the reverse cycle as the index at the start of the reverse cycle indicates that the amount of the frost on the outdoor heat exchanger is smaller.

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.

An outdoor unit includes a compressor compressing a sucked refrigerant and discharging compress, an outdoor heat exchanger exchanging heat between outdoor air and the refrigerant, an accumulator storing a liquefied refrigerant at a suction side of the compressor, a solenoid valve for storing the refrigerant in the outdoor heat exchanger, and a controller performing control so as to feed the refrigerant stored within the outdoor heat exchanger during a defrosting operation, to the accumulator on the basis of an amount of refrigerant within the accumulator when operation is switched to a heating operation from the defrosting operation.

A refrigeration system and a start control method for a refrigeration system. The refrigeration system includes: a refrigeration loop having an exhaust port of a compressor, a condenser, a throttle element, an evaporator, and a suction port of the compressor connected in sequence by using a flow path; wherein a first valve is disposed between the throttle element and the condenser, and the first valve is at least capable of cutting off a refrigerant flow from the throttle element to the condenser; and a second valve is disposed close to the suction port of the compressor, and the second valve is used to control on/off of a flow path between the evaporator and the compressor. Starting load of the refrigeration system according to the present invention can be effectively reduced, so that the power and size of a drive component for providing power can also be reduced.

Provided are a control method of a heat pump system and a heat pump system. The heat pump system includes a throttling element and a four-way valve. The four-way valve has a first state in a case that the heat pump system operates for refrigerating and a second state in a case that the heat pump system operates for heating. The control method includes that: before the four-way valve is switched from the first state to the second state, A is compared with B, and switching of the state of the four-way valve is controlled and the opening degree of the throttling element is adjusted according to the comparison result, or switching of the state of the four-way valve is controlled according to the comparison result, or the opening degree of the throttling element is adjusted according to the comparison result.

A liquid slug protector device for air conditioning and heat pump systems can include a housing having an inlet port, an outlet port, an abutment surface, and a cavity. The device can include a piston disposed in the cavity. The piston can have a primary channel. The device can include a secondary channel. A first refrigerant flow path extending between the inlet port and the outlet port can include the primary channel. A second refrigerant flow path extending between the inlet port and the outlet port can include the secondary channel. The second refrigerant flow path can be closed when the piston abuts against the abutment surface.

A gas-liquid separation device includes a cylinder, an external port, an adapter, and a gas-liquid separation component. The cylinder has a first cavity, a second cavity, and a third cavity. The external port includes a first port, a second port, and a third port. The adapter is at least partially disposed in the cylinder. The gas-liquid separation component is located in the third cavity. When the gas-liquid separation device is in a first working state, the adapter separates the third port from the third cavity, the first port serves as the inlet, and the second port serves as the outlet when the gas-liquid separation device is in a second working state, the adapter communicates the third port with the third cavity, the second port serves as an inlet, and the first port and the third port serve as outlets. The gas-liquid separation component separates gas-liquid two-phase refrigerant.