A system and method for controlling a refrigeration system is disclosed. The system includes a cooled compartment, at least one heat source selectively activated to provide heat, at least one sensor, and a controller. The sensor detects a temperature and a relative humidity of ambient air that surrounds the cooled compartment. The controller is in communication with the at least one heat source and the at least one sensor. The controller includes logic for calculating a dew point temperature based on the temperature and the relative humidity. The controller also includes logic for selecting a region of operation based on at least one of the dew point temperature and the relative humidity, where the region of operation is representative of ambient conditions that surround the cooled compartment. The controller further includes logic for determining if the at least one heat source is activated based on the region of operation.

A system and method for predicting ice gradient in refrigeration units is disclosed, comprising steps of capturing data pertaining to parameters of the refrigeration units, correlating the received parameters to generate characteristic features indicative of behaviour and performance of the one or more refrigeration units, generating events based on the generated characteristic features, identifying a frosting pattern associated with the refrigeration units by analyzing the generated events, determining a quantum of icing and a rate of ice formation in the refrigeration units based on the identified frosting pattern, and predicting ice gradient associated with the refrigeration units based on the determined quantum of icing and the rate of ice formation.

Methods are provided for controlling a refrigerated dryer of a gas compressor system. In an aspect, a control system, including a controller and a flow sensor, selectively operates in a power saving mode in which the controller shuts down a refrigerant compressor included in the dryer system when the flow sensor indicates that no compressed gas is flowing through the dryer. The control system uses input from a temperature sensor to determine whether to activate the compressor regardless of the flow of compressed gas through the dryer.

In various implementations, a heat pump may include heating operations and defrost operations. The heat pump may monitor cycle time(s) for one or more of the operations. Defrost operation(s) in the heat pump may be automatically adjusted based at least partially on cycle times.

Embodiments of the present disclosure are directed to a controller for a heating, ventilation, and/or air conditioning (HVAC) system. The controller is configured to operate in a first defrost mode or a second defrost mode, determine that feedback from a first sensor of the HVAC system is unavailable, receive feedback from a second sensor of the HVAC system, and operate the HVAC system in the second defrost mode instead of the first defrost mode in response to unavailability of the feedback from the first sensor and based on the feedback from the second sensor.

An air conditioner and a method for controlling an air conditioner are provided that inject a refrigerant into a compressor to perform a defrosting operation. The air conditioner may include a compressor; an outdoor heat exchanger; an indoor heat exchanger; a first injection module that injects a refrigerant flowing from the indoor heat exchanger to the outdoor heat exchanger into the compressor during a heating operation and that does not inject a refrigerant flowing from the outdoor heat exchanger to the indoor heat exchanger into the compressor during a defrosting operation; and a second injection module that injects a refrigerant flowing from the indoor heat exchanger to the outdoor heat exchanger into the compressor during the heating operation and that injects a refrigerant flowing from the outdoor heat exchanger to the indoor heat exchanger into the compressor during the defrosting operation.

A heat pump device includes an air conditioning control device configured to switch the heat pump device among a plurality of operation modes including an air-heating operation mode in which an indoor heat exchanger serves as a radiator and an outdoor heat exchanger serves as a heat absorber, and an air-cooling operation mode in which the indoor heat exchanger serves as a heat absorber and the outdoor heat exchanger serves as a radiator. The air conditioning control device switch a refrigerant pipe such that refrigerant is, in the air-cooling operation mode, supplied to part of the outdoor heat exchanger serving as a refrigerant inlet in the air-heating operation mode.

A heating, ventilation, and air-conditioning (HVAC) system comprises an outdoor unit with a fan and a coil, and a controller communicatively coupled to the fan and coil. The controller is operable to receive feedback data from the fan, where the feedback data from the fan corresponds to a power and a speed of the fan. The controller is further operable to store a fan model and a plurality of thresholds and determine a virtual sensor measurement, based at least in part upon the feedback data from the fan and the fan model. The controller is operable to determine that the virtual sensor measurement is greater than a frost threshold or a fouling threshold. The controller is finally operable to, in response to determining that the pressure difference is greater than the frost threshold or the fouling threshold, determine a blocked condition on the coil.

In various implementations, a heat pump may include heating operations and defrost operations. The heat pump may monitor cycle time(s) for one or more of the operations. Defrost operation(s) in the heat pump may be automatically adjusted based at least partially on cycle times.

A refrigerator includes: a main body having a storage chamber; a door for opening and closing the storage chamber; a thermoelectric module for cooling the storage chamber; an outside temperature sensor for detecting an outside temperature; a storage chamber temperature sensor for detecting the storage chamber temperature; and a control unit for applying a voltage within a range between the maximum voltage and the minimum voltage to the thermoelectric module. The control unit applies the set voltage, not the maximum voltage, to the thermoelectric module when the outside temperature is the uppermost outside temperature range among the plurality of outside temperature ranges and thus the temperature of the control is lowered and power consumption is reduced.