A dedicated outside air-conditioning system (DOAS) that may automatically generate variable subcooling refrigerant delivered to the evaporator; and modulate hot discharge gas to reduce the relative humidity of the discharge air from the DOAS. The DOAS may include fluid control valves configured to regulate delivery of the refrigerant in order to seamlessly flex between maximum latent capacity (minimum discharge dewpoint) and maximum sensible capacity (minimum leaving air discharge dry bulb temperature) to match load and/or ventilation air requirements.

A method for controlling cold storage of an air conditioner includes acquiring an ambient temperature around the air conditioner and a pipe temperature of an exhaust pipe of a compressor of the air conditioner, acquiring a target opening degree corresponding to a current cold storage mode of the air conditioner according to the ambient temperature and the pipe temperature, and adjusting an opening degree of a throttle device of the air conditioner to be the target opening degree. The throttle device is arranged at a pipe between a cold storage box of the air conditioner and a condenser of the air conditioner.

A heating and cooling system that includes a condenser coil configured to receive a refrigerant. A first compressor and a second compressor that pump the refrigerant through the condenser coil. A first condenser fan and a second condenser fan that push air over the condenser coil. A controller that receives a signal indicative of an ambient air temperature, a signal indicative of an operational status of the first compressor, and a signal indicative of an operational status of the second compressor. The controller controls operation of the first condenser fan and the second condenser fan in response to the signal indicative of the ambient air temperature, the signal indicative of the operational status of the first compressor and the signal indicative of the operational status of the second compressor.

An HVAC system includes a controller communicatively coupled to a subcool sensor, an outdoor temperature sensor, a compressor, and a blower of the HVAC system. For a first period of time, the controller periodically determines subcool values. For each determined subcool value, a corresponding compressor speed, outdoor temperature, and blower speed are determined. A baseline database is generated with baseline values associated with normal operation of the HVAC system. Following the first period of time, subcool values are determined based on the subcool signal. For each subcool value, a corresponding compressor speed, outdoor temperature, and blower speed are determined. The controller determines whether each subcool value satisfies a criteria based on the baseline database. If the criteria are not satisfied for at least a threshold time, the system is determined to be operating under a fault condition, and a corresponding alert is transmitted.

A refrigerant measurement adjustment system includes: a refrigerant sensor for a building and configured to measure an amount of refrigerant present in air outside of a refrigeration system of the building; and an adjustment module configured to: adjust the amount of refrigerant measured based on an adjustment to produce an adjusted amount; and determine the adjustment based on at least one of: an air temperature; an air pressure; a relative humidity of air; a mode of operation of the refrigeration system; a change in the measurements of the refrigerant sensor over time; and whether a blower that blows air across a heat exchanger of the refrigeration system located within the building is on.

Disclosed are climate systems and methods for control the climate systems. A climate system includes a plurality of compressors, a first heat exchanger disposed downstream of the compressors and a second heat exchanger disposed downstream of the first heat exchanger. The compressors and heat exchangers are fluidly connected by refrigerant lines to form a refrigerant circuit. The climate system also includes a controller that controls the operation of the compressors to draw back lubricant to the compressors without use of an oil equalization system.

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.

Provided is a control method on electronic expansion valve in air conditioner comprises: obtaining a real-time running frequency of compressor, a real-time exhaust temperature and a real-time outdoor environment temperature as the compressor running; comparing the real-time running frequency of compressor with a first set frequency; if the real-time running frequency is greater than or equal to the first set frequency, obtaining an integral coefficient of the PID algorithm according to a first set rule; if the real-time running frequency is less than the first set frequency, obtaining an integral coefficient of the PID algorithm according to the comparison of the real-time outdoor environment temperature and the first set outdoor environment temperature and a second set rule, or according to the comparison of the real-time outdoor environment temperature and the first set outdoor environment temperature and a third set rule, wherein the selection is based on whether the air conditioner is working in cooling mode or in heating mode; performing a PID control on the electronic expansion valve by an error of the difference between real-time exhaust temperature and a set target exhaust temperature. The method realizes an accurate and stable control on electronic expansion valve opening amount.

A refrigeration cycle apparatus (1) is capable of performing a refrigeration cycle using a small-GWP refrigerant. The refrigeration cycle apparatus (1) includes a refrigerant circuit (10) and a refrigerant enclosed in the refrigerant circuit (10). The refrigerant circuit includes a compressor (21), a condenser (23), a decompressing section (24), and an evaporator (31). The refrigerant contains is a small-GWP refrigerant.

The disclosed technology includes devices, systems, and methods for heat pump systems configured to operate in low ambient temperatures. The disclosed technology can include a heat pump water heater system having an evaporator, a first compressor configured to compress refrigerant to a first pressure, and a second compressor configured to compress the refrigerant to a second pressure. The second pressure can be greater than the first pressure. The heat pump water heater system can include a preheater configured to receive the refrigerant at the first pressure and heat water and a condenser configured to receive the refrigerant at the second pressure and heat water. The water can be passed through the preheater before being passed through the condenser.