A desiccant air conditioning system for treating an air stream entering a building space, including a conditioner configured to expose the air stream to a liquid desiccant such that the liquid desiccant dehumidifies the air stream in the warm weather operation mode and humidifies the air stream in the cold weather operation mode. The conditioner includes multiple plate structures arranged in a vertical orientation and spaced apart to permit the air stream to flow between the plate structures. Each plate structure includes a passage through which a heat transfer fluid can flow. Each plate structure also has at least one surface across which the liquid desiccant can flow. The system includes a regenerator connected to the conditioner for causing the liquid desiccant to desorb water in the warm weather operation mode and to absorb water in the cold weather operation mode from a return air stream.

In one embodiment, an HVAC system includes an indoor unit having a furnace, an outdoor heat pump unit having a compressor and an outdoor coil, a refrigerant line coupled to the indoor unit and the outdoor heat pump unit, and an EEV coupled to the refrigerant line. The HVAC system further includes one or more controllers operable to determine an occurrence of a first event, initiate a closure of the EEV, initiate operation of the compressor at a completion of the air conditioning cycle to pump down a refrigerant to the outdoor coil, and cease operation of the compressor when a low-pressure switch is tripped.

In one embodiment, an HVAC system includes an indoor unit having a furnace, an outdoor heat pump unit having a compressor and an outdoor coil, a refrigerant line coupled to the indoor unit and the outdoor heat pump unit, and a valve coupled to the refrigerant line. The HVAC system further includes one or more controllers operable to determine that the outdoor heat pump unit is in operation during an air conditioning cycle. The controllers are further operable to determine an outdoor temperature and compare the outdoor temperature to a predetermined temperature. The controllers are further operable to initiate a closure of the valve coupled to the refrigerant line and initiate operation of the compressor at an end of the air conditioning cycle to pump down a refrigerant to the outdoor coil in response to comparing the outdoor temperature to the predetermined temperature.

In order to improve safety in a refrigerant compressor system comprising a refrigerant compressor and an electric drive motor for driving the refrigerant compressor, and, arranged in a protected manner in an interior of a control housing, a control electronics system, comprising electric components or electronic power components, for controlling the electronic drive motor, it is proposed that, during operation of the refrigerant compressor system with combustible refrigerant, the control housing is provided with a refrigerant drain, which does not impair at least one protection criterion of the control housing, for discharging refrigerant which enters the interior due to a refrigerant leakage, said refrigerant drain causing the refrigerant entering into the interior due to the refrigerant leakage to pass out of the interior into the surroundings of the refrigerant compressor system.

A dehumidifying apparatus includes first, second, and third heat exchangers; moisture adsorbing material; a fan to force air through the first heat exchanger, the moisture adsorbing material, the second heat exchanger, and the third heat exchanger; a compressor having a discharge side connected to the third heat exchanger; and an expansion valve configured to reduce the pressure of a refrigerant condensed by the first heat exchanger or the second heat exchanger. The third heat exchanger has a fin pitch smaller than a fin pitch of the first heat exchanger and a fin pitch of the second heat exchanger. The third heat exchanger is smaller than the first heat exchanger and the second heat exchanger. This arrangement provides a small, low-cost dehumidifying apparatus.

An air conditioning system includes an outdoor air latent cooling treatment stage providing parallel airflow with a return air sensible cooling treatment stage. A mixer mixes the treated outdoor air with the return air to form the conditioned space supply air. A first relative humidity controller monitors the outdoor air relative humidity and separates the outdoor air from saturation to maintain relative humidity in outdoor air ducting below a predetermined mould growth limit. A second relative humidity controller monitors the conditioned space supply air relative humidity and separates the space supply air from saturation to maintain relative humidity in space supply air ducting below a predetermined mould growth limit. The outdoor air latent cooling treatment stage includes a dehumidification heat exchanger, combination pre-cooling and heat reclaim heat exchangers, or a heat transfer pump. The return air sensible cooling treatment stage includes at least a sensible cooling heat exchanger.

An air conditioner includes: a cooling unit having a compressor operated at a variable operating frequency to adjust a revolving speed thereof, a condenser, an expansion valve and a cooling coil; and a heating unit for causing the heating medium flowing from the compressor toward the condenser to diverge, and to return to flow into the condenser, through a heating coil and a thermal dose adjusting valve disposed on the downstream side thereof; so as to control a temperature of air by the cooling and heating coils. When an opening manipulated variable of the thermal dose adjusting valve exceeds a first threshold value over a period of time, an operating frequency of the compressor is decreased, and when the opening manipulated variable of the thermal dose adjusting valve falls below a smaller, second threshold value, over the said period of time, the operating frequency of the compressor is increased.

A cooling and dehumidification system, including a rotary desiccant assembly at least partially coated with a desiccant material, the desiccant material configured to rotate, thereby providing for simultaneous loading and unloading of moisture.

Air conditioner units and methods for operating air conditioner units are provided. A method includes determining a benchmark control signal corresponding to a predetermined speed of a fan of the air conditioner unit. The method further includes activating a heating unit of the air conditioner unit. The heating unit includes a plurality of heater banks. The method also includes activating the fan while the heating unit is active and measuring a control signal to the fan after activating the fan. The method further includes comparing the measured control signal to the benchmark control signal, and disabling one of the plurality of heater banks when the measured control signal is less than the benchmark control signal.

In an air conditioning system, a thermal source device generates cold water from cooling water cooled by a cooling tower. A cooling water circulation passage allows circulation of the cooling water between the cooling tower and the thermal source device. A first heat exchanger exchanges heat between air and the cold water. A cold water circulation passage allows circulation of the cold water between the thermal source device and the first heat exchanger. A second heat exchanger exchanges heat between the cooling water cooled by the cooling tower and the air heat-exchanged with the cold water by the first heat exchanger. A cooling water branch passage, introduces to the second heat exchanger the cooling water introduced to the thermal source device from the cooling tower, and introduces to the cooling water circulation passage the cooling water heat-exchanged with the air by the second heat exchanger.