An integrated sensor and service port for HVAC (heating, ventilating, and air conditioning) equipment or an HVAC system. The integrated sensor and service port may comprise an anti-blowback mechanism.

Example embodiments of the present disclosure relate to an HVAC system, and methods for controlling the system, that mitigate the impact of refrigerant leaks before the leaks are even detected. Some embodiments include an HVAC system operable to mitigate refrigerant leaks, the system including an indoor unit including an indoor fan and an indoor heat exchanger, an outdoor unit including an outdoor heat exchanger and a compressor, a refrigerant circuit including a refrigerant circulated between the indoor unit and the outdoor unit, a mass control valve coupled to the refrigerant circuit, and control circuitry configured to: operate the HVAC system to satisfy a conditioning load by circuiting the refrigerant through the refrigerant circuit and operating the indoor fan, and completely close the mass control valve to at least partially isolate the refrigerant circuit at the indoor heat exchanger in response to the indoor fan being shut off.

A heat cycle system and a control method. The heat cycle system includes: driving devices, one or a plurality of outdoor units, and a plurality of indoor units, which are connected by pipelines; a bypass pipeline for the plurality of indoor units, a bypass valve being disposed in the bypass pipeline; a pressure sensor that senses a pressure difference ΔP.sub.o across the plurality of outdoor units; and a controller that is preset with a pressure difference set value ΔP.sub.set, wherein the controller calculates a pressure offset parameter ΔP=ΔP.sub.o−ΔP.sub.set and adjusts an opening degree of the bypass valve based on the pressure offset parameter ΔP so that the pressure offset parameter ΔP approaches zero, and wherein the controller is preset with a first pressure offset threshold P.sub.1, and the controller is configured such that closed indoor units enter a bypass mode one by one when ΔP>P.sub.1, until ΔP≤P.sub.1.

A liquid level detector includes: a vertically-mounted accumulator configured to store refrigerant; a heater configured to heat the accumulator; a temperature detector configured to detect a surface temperature of the accumulator; a pressure detector configured to detect a pressure of the refrigerant in the accumulator; and a controller configured to detect a position of a liquid surface of the refrigerant in the accumulator based on a surface temperature of the accumulator detected by the temperature detector when the accumulator is heated by the heater, and a pressure of the refrigerant in the accumulator detected by the pressure detector.

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.

A packaged, pumped liquid, evaporative-condensing recirculating ammonia refrigeration system with charges of 10 lbs or less of refrigerant per ton of refrigeration capacity. The compressor and related components are situated inside the plenum of a standard evaporative condenser unit, and the evaporator is close coupled to the evaporative condenser. Single or dual phase cyclonic separators may also be housed in the plenum of the evaporative condenser.

An HVAC system includes an unloading device, a centrifugal compressor, a gas foil bearing, a VFD and a controller. The controller is programmed to start the centrifugal compressor from a stopped condition by operating the unloading device to remove a load from the centrifugal compressor, accelerating the motor to a first speed above a liftoff speed of the gas foil bearing and below an operating speed of the centrifugal compressor, running the motor for a period of time, operating the unloading device to apply the load to the centrifugal compressor, and accelerating the motor to the operating speed.

A sensor control system includes: a refrigerant leak sensor configured to, when powered, measure an amount of a refrigerant present in air outside of a heat exchanger of a refrigeration system, where the heat exchanger is located within a building that is at least one of heated and cooled by the refrigeration system; and a power control module configured to one of: continuously power the refrigerant leak sensor; and disconnect the refrigerant leak sensor from power when a blower that moves air past the heat exchanger is on.

An air-conditioning apparatus includes a low-pressure-side pressure sensor that detects the pressure of heat-source-side refrigerant that flows into a compressor and outputs it as a first detection value and a high-pressure-side pressure sensor that detects the pressure of heat-source-side refrigerant discharged from the compressor and outputs it as a second detection value. When switching the operation mode of the apparatus, a controller determines whether the ratio of the first detection value to the second detection value is higher than a first threshold. When the ratio is higher than the threshold, the controller causes a second refrigerant flow switching device to perform a switching operation. When the ratio is less than or equal to the threshold, the controller makes an adjustment such that an opening degree of an expansion device is less than a second threshold, and then causes the second refrigerant flow switching device to perform the switching operation.

A refrigeration system comprising a main refrigeration circuit including a compression stage, a condensing stage, and an evaporation stage, a refrigerant circulating between the compression stage, the condensing stage and the evaporation stage in a refrigeration cycle. An integrated transfer system is in closeable and openable fluid communication with the main refrigeration circuit, the transfer system including a receiver. Valves are operable to selectively open the fluid communication between the main refrigeration circuit and the transfer system. A motive force source displaces refrigerant from the main refrigeration circuit to the transfer system.