An HVAC system includes a compressor, condenser, and evaporator. A sensor measures a value associated with the refrigerant in the condenser or the evaporator, and a controller is communicatively coupled to the compressor and the sensor. The controller determines, based on an operational history the compressor, that pre-requisite criteria are satisfied for entering a sensor validation mode. After determining the pre-requisite criteria are satisfied, an initial sensor measurement value is determined. Following determining the initial sensor measurement value, the compressor is operated according to a sensor-validation mode. Following operating the compressor according to the sensor-validation mode for at least a minimum time, a current sensor measurement value is determined. The controller determines whether validation criteria are satisfied for the current sensor value. In response to determining that the validation criteria are satisfied, the controller determines that the sensor is validated.

Systems and methods for monitoring refrigeration appliances remotely take corrective action to address failure to maintain recurrent maintenance schedules by either pushing a notification to an operator or sending a command to cause a controller of the appliance to switch to a restricted mode. The systems and methods can use periodic indications of ice level from an ice level sensor to determine that the level of ice in the bin is low, and in response, to either push a low ice notification to an operator or place an order for additional ice. The systems and methods can also collect ice level data from many ice makers, determine which have a low ice level and which have a high ice level, and in response, facilitate a web based transaction by which one operator acquires ice from another.

A cooling system for cooling a machine tool having a machine temperature. The cooling system comprises gas source, refrigeration circulation, fan, and controller. The gas source is configured for providing gas. The refrigeration circulation comprises heat exchanger, compressor, condenser, and expansion valve. The heat exchanger is in fluid communication with the gas source and configured to cool the gas down to target temperature and to provide the gas to the machine tool. The compressor has operation frequency. The fan is configured to cool the condenser and has a rotation speed. The controller is connected to the compressor and the fan. When a target temperature difference that is equal to the machine temperature minus the target temperature is smaller than threshold temperature difference, the controller keeps the operation frequency at minimum frequency and sets the rotation speed to be smaller than a maximum rotation speed.

An air cooled oil-free centrifugal chiller system and method, the system comprising at least one AC condenser fan; at least one solar panel; at least one AC/DC convertible fan connected to the at least one solar panel; and a controller configured to determine when sufficient DC power is available and activating the at least one AC/DC convertible fan when sufficient DC power is available, and when DC power is not sufficient, activating the at least one AC condenser fan.

A method of minimizing components of a heating, ventilation, and air conditioning (HVAC) system from malfunctioning, the method includes measuring, by an accelerometer associated with at least one component of the HVAC system, vibration of the at least one component and receiving, by a controller, actual vibration data reflective of the measured vibration. The method further includes determining, using the controller, whether the actual vibration data is greater than pre-defined acceptable baseline vibration data by more than a pre-defined acceptable amount and responsive to a positive determination in the determining step, adding, by the controller, as a deadband frequency, an operational frequency of the at least one component corresponding to the actual vibration data.

An HVAC system includes a compressor, condenser, and evaporator. A sensor measures a value associated with the refrigerant in the condenser or the evaporator, and a controller is communicatively coupled to the compressor and the sensor. The controller determines, based on an operational history the compressor, that pre-requisite criteria are satisfied for entering a sensor validation mode. After determining the pre-requisite criteria are satisfied, an initial sensor measurement value is determined. Following determining the initial sensor measurement value, the compressor is operated according to a sensor-validation mode. Following operating the compressor according to the sensor-validation mode for at least a minimum time, a current sensor measurement value is determined. The controller determines whether validation criteria are satisfied for the current sensor value. In response to determining that the validation criteria are satisfied, the controller determines that the sensor is validated.

An HVAC system including a multi-capacity compressor, and a control system for the multi-capacity compressor are described herein. The control system includes an AC line voltage source, a variable-voltage variable-frequency drive, and a processor. The AC line voltage source is configured to operate the multi-capacity compressor. The variable-voltage variable-frequency drive is coupled to the AC line voltage source and is configured to operate the multi-capacity compressor at a variable speed. The processor is coupled to the AC line voltage source and the variable-voltage variable-frequency drive and is configured to selectively couple the AC line voltage source and the variable-voltage variable-frequency drive to the multi-capacity compressor to operate the multi-capacity compressor. The processor is further configured to transmit a capacity control signal to the multi-capacity compressor. The capacity control signal is instructive to operate the multi-capacity compressor in one of a plurality of capacity settings.

Thermal management systems are described. These systems include a refrigerant receiver configured to store a refrigerant fluid, an evaporator, a closed-circuit refrigeration system having a closed fluid circuit path, with the refrigerant receiver and evaporator disposed in the closed fluid circuit path, and the closed fluid circuit path including a condenser and compressor. These systems also include a modulation capacity control circuit configured to selectively divert refrigerant vapor flow to the condenser from the compressor by diverting a portion of refrigerant vapor flow (diverted flow) from the compressor to the refrigerant receiver in accordance with cooling capacity demand. These systems also include an open-circuit refrigeration system having an open fluid circuit path with the refrigerant receiver and the evaporator, and an exhaust line that discharges the refrigerant fluid from the exhaust line so that the discharged refrigerant fluid is not returned to the open-circuit and the closed-circuit refrigerant fluid flow paths.

Disclosed herein are air conditioning systems including a refrigerant line configured to transport a refrigerant; a compressor in fluid communication with the suction line; and a controller in communication with a sensor configured to measure a characteristic of the refrigerant line. The compressor can be configured to move the refrigerant through the refrigerant line, and the refrigerant can have a first temperature at the outlet of the compressor. The controller can be configured to receive sensor data from the sensor indicating a current value associated with the characteristic of the refrigerant line; determine, based at least partially on the sensor data, that the characteristic of the refrigerant line is above a predetermined threshold; and output instructions for the compressor to perform one or more corrective actions.

A heat exchanger includes: a gas-refrigerant pipe; a header connected to the gas-refrigerant pipe; and heat transfer tubes connected to the header. The header includes: a first plate member; and a second plate member that is stacked on the first plate member in a plate-thickness direction. The first plate member includes a first opening that constitutes an internal space of the header. The second plate member includes a second opening that, together with the first opening, constitutes the internal space of the header. The internal space of the header communicates with the heat transfer tubes. A first direction is perpendicular to both the plate-thickness direction and a direction in which the heat transfer tubes are arranged. A width of a part of the first opening in the first direction is different from a width of the second opening in the first direction.