In order to improve the operational reliability of a refrigerant compressor system that includes a first refrigerant line that conducts expanded refrigerant, a second refrigerant line that conducts compressed refrigerant, at least one refrigerant compressor that is arranged between the first and the second refrigerant line and is driven by a motor, and a control unit for operating the refrigerant compressor system, it is proposed that the control unit should have a first central processing unit and at least one input/output unit for control variables that communicates with the first central processing unit, and that there should be associated with the first central processing unit a second central processing unit which, in the event of a failure of the first central processing unit, takes over the control functions for the purpose of controlling the refrigerant compressor system.

A multi-type air conditioning device controls an evaporation temperature and a condensing temperature, depending on required capacity of an indoor unit. The air conditioning device compares a current evaporation temperature or condensing temperature with a reference value, of an evaporation temperature or an condensing temperature, corresponding to a lower limit flow rate, of a gaseous refrigerant, required for refrigerating machine oil not to accumulate in, but to flow through, the gas branch pipes, and calculates an amount of the refrigerating machine oil accumulated in a gas branch pipe which does not satisfy the lower limit flow rate. When the calculated amount exceeds a set amount, the air conditioning device performs oil collecting operation, and controls the oil collecting operation in view of a flow rate of a gaseous refrigerant in gas branch pipes.

A motor drive apparatus includes a power converter including an inverter having an upper arm and a lower arm, the inverter being configured to control an operation of an electric motor, and a drive controller configured to apply a dead time for preventing a short circuit between the upper arm and the lower arm, and to control the power converter. The drive controller is configured to control the power converter by switching a first mode in which a first correction value representing a time used to correct a voltage drop due to the dead time is employed to control the power converter, and a second mode in which a second correction value smaller than the first correction value is employed to control the power converter.

Heating and cooling optimization systems are disclosed. Such systems may include a superheater and desuperheater are disclosed. An example superheater may include a combined suction line accumulator and heat exchanger configured to receive a heated fluid from an external source. An example desuperheater may comprise an accumulation tank and a heat exchanger configured to receive a relatively cool fluid from an external source. Various external sources may be a solar thermal source, a wood chip boiler, a ground loop, a geothermal source, an attic space, a garage, and/or a chemical heat source. Disclosed heating and cooling systems may include a controller sub-system for selectively modulating a flow rate of heated fluid through the superheater and for selectively modulating a flow rate of cooled fluid through the desuperheater.

A chiller is provided that includes a deionization filter to remove ionic substances in cooling waters, and that is of such a small size as to save energy and costs. The chiller also includes cooling-water circuits, and a refrigeration circuit. The refrigeration circuit includes heat-exchange-path sections. The heat-exchange-path sections include respective heat exchangers. The cooling-water circuits and includes tanks, first supply lines, second supply lines, and return lines. The chiller includes a filtering line branching off from the second supply line of the cooling-water circuit and connected to the return line of the cooling-water circuit. The filtering line is provided with the deionization filter.

A water distribution apparatus and method including cold and hot water supplies, a fan coil (or chilled beam device), a control valve having cold and hot water inlets and outlets, cold and hot water outputs configured to supply cold and hot water to the fan coil, cold and hot water return inlets configured to receive from the fan coil the water supplied by the cold and/or water outputs and outputting the cold and/or hot water to the cold and hot water supply lines, respectively, via the cold and hot water outlets, respectively. Cold and hot water is supplied from the cold and/or hot water outputs to the fan coil and received into the cold and hot water return inlets, respectively, and the cold and hot water supplied by the cold and hot water outputs to the fan coil is output to the cold and hot water supply lines, respectively.

An HVAC system includes an evaporator. The evaporator includes a sensor configured to measure a property value (i.e., a saturated suction temperature or a saturated suction pressure) associated with saturated refrigerant flowing through the evaporator. The system includes a variable-speed compressor configured to receive the refrigerant and compress the received refrigerant. The system includes a controller communicatively coupled to the sensor and the variable-speed compressor. The controller monitors the property value measured by the sensor and detects a system fault, based on the monitored property value. In response to detecting the system fault, the controller operates the compressor in a freeze-prevention mode, which is configured to maintain the property value above a setpoint value by adjusting a speed of the variable-speed compressor. This prevents or delays freezing of the evaporator during operation of the system during the detected system fault.

Thermal energy systems for managing, distribution and recovery of thermal energy. A single-pipe loop circulating a two-phase refrigerant is provided. The single-pipe loop is spread through the entire system and interconnects a plurality of local heat exchange stations, each having different thermal energy loads. A central circulation mechanism (CCM) is also provided for circulating the refrigerant for distribution of thermal energy within the system.

According to one embodiment, in a low speed drive of outdoor fans, a first flow rate adjusting valve in a main outdoor heat exchanger side is narrowed to a closing degree or a close range thereof, and an opening degree of a second flow rate adjusting valve is controlled such that a supercooling degree of refrigerant in auxiliary outdoor heat exchangers becomes constantly a target value.

An evaporator apparatus for a refrigeration cycle of an HVAC system or a refrigeration system is disclosed that includes: a primary evaporator pathway for a working fluid of the refrigeration cycle extending through a primary expansion device and a primary evaporator; a secondary evaporator pathway for the working fluid in parallel with the primary evaporator pathway and extending through a secondary expansion device and a secondary evaporator; a coolant circuit for cooling a device, the secondary evaporator configured for heat exchange between the working fluid and process fluid of the coolant circuit; and a controller configured to control: the primary expansion device to maintain a target superheat of working fluid at a primary control location downstream of the primary evaporator; and the secondary expansion device based on monitoring a temperature of process fluid to maintain a target temperature of process fluid at a coolant control location in the coolant circuit.