A free cooling outdoor unit includes: a refrigerant circuit through which refrigerant circulates; a brine circuit through which brine circulates; a water circuit through which water circulates; a fan configured to send air to the second heat exchanger; a flow control valve configured to control a circulation amount of the brine in the brine circuit; a water temperature detection sensor configured to detect a water temperature in the water circuit; an outside air temperature sensor; and a controller configured to control, where the outside air temperature is equal to or lower than a freezing temperature of the brine, the circulation amount of the brine based on the water temperature such that a brine temperature is prevented from reaching a temperature equal to or lower than the freezing temperature of the brine.

A heat pump system includes a compression device 12, a heat rejecting heat exchanger 14, an expansion device 18 and a heat absorbing heat exchanger 16; wherein the expansion device 18 provides a controllable degree of expansion. The heat pump system is operated in accordance with a method including determining a temperature indicative of frosting conditions on an exterior surface of the heat absorbing heat exchanger 16; operating the heat pump system in a first mode if the temperature indicative of frosting conditions is above a threshold value, and operating the heat pump system in a second mode if the temperature indicative of frosting conditions is within a range of temperatures that is below the threshold value.

This disclosure relates to cold-chain transportation, and more particularly to a refrigerated container refrigeration system capable of preventing freezing of container door, including compressors, oil separators, gas coolers, regenerators, electronic expansion valves, gas-liquid separators, an evaporator, suction pressure regulating valves, oil-level solenoid valves, gas cooler pressure regulating valves, differential pressure regulating valves, an evaporation pressure regulating valve, solenoid valves, check valves, flow meters, pressure sensors, temperature sensors, a door anti-freezing area, a refrigerated container shell, refrigerated container doors, a refrigeration unit, an anti-freezing pipeline and fastening components. Carbon dioxide is selected as refrigerant. A flow two-stage cycle compression refrigeration system with switchable operation pipeline is adopted, and the outlet pipeline of a high-pressure compressor is extended for preventing freezing of container door.

A refrigeration system includes a startup mode control module that receives an off time of a compressor and an ambient temperature, determines whether the off time and the ambient temperature indicate that the compressor is in a flooded condition, and selects, based on the determination, between a normal startup mode and a flooded startup mode. A compressor control module operates the compressor in the normal startup mode in response to the startup mode control module selecting the normal startup mode, operates the compressor in the flooded startup mode in response to the startup mode control module selecting the flooded startup mode, and transitions from the flooded startup mode to the normal startup mode after a predetermined period associated with operating in the flooded startup mode.

A hydronic economizer module is configured for use in a chiller system that has a vapor compression cycle. The hydronic economizer module includes a heat exchanger assembly located within a housing having at least one heat exchanger coil, a fan assembly having at least one fan generally aligned with at least one heat exchanger coil, and at least one valve is movable between a plurality of positions to control a flow of fluid into the heat exchanger assembly. When the at least one valve is in a first position, the economizer module is arranged in parallel with a flat plate heat exchanger. When the at least one valve is in a second position, the economizer module is arranged in series with the flat plate heat exchanger. The flat plate heat exchanger includes at least one fluid port for communicating with a component of the vapor compression cycle.

A cooling and heating system for a motor vehicle comprises a heat pump, a controller, a low temperature radiator in thermal communication with the heat pump, a passenger cabin heat exchanger in thermal communication with the heat pump, and a defrost system comprising a bypass coolant loop in selective fluid communication with the low temperature radiator. When in the heating mode, the controller opens a solenoid valve and activates a coolant heater in the bypass coolant loop upon detecting operation of the heat pump outside of a predetermined normal operating range and upon detecting an ambient temperature below a predetermined temperature. The controller de-activates the coolant heater upon detecting operation of the heat pump within the predetermined normal operating range. The controller may also de-activate close the solenoid upon detecting operation of the heat pump within the predetermined normal operating range.

The motor-driven compressor includes an electric motor, a housing, a compression portion, and an inverter device. The inverter device includes an inverter circuit, a current sensor, a coordinate converter, a speed controller, a current controller, a PWM controller, and a rotation angle estimator. The speed controller generates a d-axis current command value and a q-axis current command value such that a necessary torque to drive the electric motor occurs. The inverter device includes a heat-generating current command section that increases a temperature of the electric motor by changing the d-axis current command value and the q-axis current command value. The heat-generating current command section changes the d-axis current command value and the q-axis current command value so as to shift them in a direction in which a d-axis current value increases along a constant torque curve in a d-q coordinate system.

A cooling system is designed to generally allow for one or more compressors to be bypassed when ambient temperatures are low. The system includes a bypass line and valve that opens when ambient temperatures are low and/or when the pressure of the refrigerant in the system is low. In this manner, the refrigerant can flow through the bypass line instead of through one or more compressors. These compressors may then be shut off. To supply any needed pressure to cycle the refrigerant, the system may include a pump that turns on when the bypass line is open. When ambient temperatures are extremely low, thermosiphon may be used to cycle the refrigerant.

A method for controlling the temperature of a compressor having a motor including a rotor and a stator, and a control assembly operably coupled to the compressor, the method comprising the steps of: applying an initial current to the compressor motor; measuring a voltage across the compressor motor and determining a resistance of the compressor motor based on the initial current and a measured voltage; determining whether the determined resistance is less than or equal to a desired resistance; applying a secondary current to the compressor motor if the determined resistance is less than or equal to the desired resistance.

A vapor compression system includes a first conduit fluidly coupling a liquid collection portion of a condenser and an evaporator, where the first conduit is configured to direct a first flow of refrigerant from the condenser to a first inlet of the evaporator and a second conduit fluidly coupling the liquid collection portion of the condenser and the evaporator, where the second conduit is configured to direct a second flow of refrigerant from the condenser to a second inlet of the evaporator via gravitational force, and where the first inlet is disposed above the second inlet relative to a vertical dimension of the evaporator.