A refrigeration-type chiller includes a coolant circuit that supplies a coolant to a load, a refrigeration circuit that adjusts the temperature of the coolant, and a control unit that controls the chiller as a whole. The control unit includes a temperature setting unit that sets, as an adjustment target temperature, the temperature of the coolant for causing the load to be at a target temperature, a time setting unit that sets an adjustment time during which to change the temperature of the coolant to the adjustment target temperature, an arithmetic unit that calculates a gradient of temperature change as a target temperature gradient from the adjustment target temperature and the adjustment time, and a temperature control unit that adjusts the opening degrees of first and second electronic expansion valves and so that the temperature of the coolant changes in accordance with the target temperature gradient.

A method of detecting electrical failure in a refrigeration system is provided. The method includes determining whether a present superheat of the refrigeration system is between a maximum superheat and a minimum superheat for the refrigeration system, the maximum superheat and the minimum superheat defining a normal operating range. The method also includes detecting an electrical property of an expansion valve assembly of the refrigeration system responsive to the superheat being outside the normal operating range. The method further includes determining whether the expansion valve assembly as experienced an electrical failure based on at least the electrical property. A signal indicating that the expansion valve has experienced an electrical failure is generated based on a determination that the expansion valve assembly has experienced the electrical failure.

A bypass line is described that is capable of equalizing pressure within an HVAC system. The bypass line can also cause less noise than other solutions. A bypass line under the present disclosure can comprise a line from a high pressure side to a low pressure side of an HVAC system. Valves and orifices can be disposed within the bypass line. The valves and orifices help to slow the speed of fluid from high pressure to low pressure locations, thus reducing noise during pressure equalization.

A refrigeration system includes a subcooler configured to provide subcooling for a liquid refrigerant flowing through a first side of the subcooler by transferring heat from the liquid refrigerant to a gas refrigerant flowing through a second side of the subcooler. An expansion valve is located at an inlet of the second side of the subcooler and configured to control a flow of the gas refrigerant through the second side of the subcooler. A gas temperature sensor and a gas pressure sensor are configured to measure a temperature and pressure of the gas refrigerant. A liquid temperature sensor is configured to measure a temperature of the subcooled liquid refrigerant. A controller is configured to calculate a superheat of the gas refrigerant based on the measured temperature and measured pressure of the gas refrigerant and may compare the calculated superheat to a superheat threshold. If the calculated superheat is less than the superheat threshold, the controller may close the expansion valve. If the calculated superheat is equal to or greater than the superheat threshold, the controller may operate the expansion valve using a feedback control technique to drive the temperature of the subcooled liquid refrigerant to a subcooled liquid temperature setpoint.

A controller for a refrigeration system includes a processing circuit having one or more processors and memory. The processing circuit is configured to calculate a superheat of a gas refrigerant exiting a first side of a subcooler based on a measured temperature and a measured pressure of the gas refrigerant and compare the calculated superheat to a superheat threshold. In response to a determination that the calculated superheat is less than the superheat threshold, the processing circuit closes an expansion valve to restrict a flow of the gas refrigerant through a second side of the subcooler. In response to a determination that the calculated superheat is equal to or greater than the superheat threshold, the processing circuit operates the expansion valve to drive a temperature of a subcooled liquid refrigerant exiting the second side of the subcooler to a subcooled liquid temperature setpoint.

An air conditioner includes a refrigerant charge port provided in an outdoor liquid-side connection valve or an outdoor gas-side connection valve, a liquid-side valve provided between the outdoor liquid-side connection valve and an expansion valve, and a gas-side valve between the indoor gas-side connection valve and a compressor. When an outdoor unit and indoor unit are separated, the liquid-side and gas-side valves are closed, and a refrigerant is charged into an outdoor connection pipe that is closed by the liquid-side valve and the gas-side valve. A control unit is adapted to close the refrigerant charge port, and then open the liquid-side valve and the gas-side valve when a pressure detector detects a predetermined degree of vacuum.

A method of determining charge loss of a refrigeration system includes the steps of inputting an ambient temperature, a box temperature, and a compressor speed into an electronic controller of the refrigeration system, and calculating a first air side temperature difference across an evaporator by applying an algorithm having a first T-Map representative of normal operating conditions. The controller may then confirm a detection prerequisite is satisfied. Upon confirmation, the controller calculates a second air side temperature difference across the evaporator by applying the algorithm having a second T-Map representative of a loss of refrigerant charge. An action may then be taken from the controller if the first air side temperature difference is less than the second air side temperature difference.

A method for controlling an electronic expansion valve of a variable refrigerant flow air conditioning system includes steps as follows: when operating in a primary heating mode, obtaining a degree of superheat of return air of a compressor, and performing a control on an opening degree of the first electronic expansion valve according to the degree of superheat; judging the degree of superheat and the opening degree of each refrigerating indoor machine in the plurality of indoor machines; and if the degree of superheat is greater than a first preset degree of superheat and an opening degree in any refrigerating indoor machine reaches a maximum opening degree, obtaining a target medium pressure value by calculating a refrigerant volume of the refrigerating indoor machine reaching the maximum opening degree, and performing a medium pressure control on the first electronic expansion valve according to the target medium pressure value.

In certain embodiments, a transcritical refrigeration system provides refrigeration by circulating refrigerant through the system. The system includes a gas cooler, a heat exchanger, a high pressure expansion valve, a flash tank, refrigeration cases, and compressors. The gas cooler cools the refrigerant to a first temperature. The heat exchanger cools the refrigerant flowing from the gas cooler to the high pressure expansion valve to a second temperature. The high pressure expansion valve is coupled to the flash tank, which is coupled to the refrigeration cases. The refrigeration cases are coupled to the compressors, which are coupled to the gas cooler. An expansion valve between the gas cooler and the heat exchanger may cool the refrigerant flowing to the heat exchanger. A high pressure vapor compressor between the heat exchanger and the gas cooler may compress the refrigerant flowing from the heat exchanger to the gas cooler.

A bypass line is described that is capable of equalizing pressure within an HVAC system. The bypass line can also cause less noise than other solutions. A bypass line under the present disclosure can comprise a line from a high pressure side to a low pressure side of an HVAC system. Valves and orifices can be disposed within the bypass line. The valves and orifices help to slow the speed of fluid from high pressure to low pressure locations, thus reducing noise during pressure equalization.