A heat pump system includes a first bypass pipe provided with a first bypass valve and connecting a liquid refrigerant pipe and a low-pressure refrigerant pipe, a refrigerant heat exchanger configured to cause a heat-exchange between refrigerant flowing in the liquid refrigerant pipe and refrigerant flowing in first bypass pipe, a second bypass pipe provided with a second bypass valve and connecting the liquid refrigerant pipe and the low-pressure refrigerant pipe, and a controller. The controller is configured to control opening degree of the first bypass valve based on detected superheated temperature of refrigerant flowing in the first bypass pipe, and detected discharge temperature of a compressor and control opening degree of the second bypass valve based on the detected discharge temperature.

Provided is an air conditioning apparatus that is capable of suppressing increases in volume and cost of the apparatus and performing more suitable overheating protection. An electric compressor is an inverter-integrated electric compressor (10) integrally including a compressor (5), an electric motor (6) that drives the compressor (5), and an inverter (7) including a temperature sensor (11) that detects the temperature in the vicinity of a semiconductor switching device, wherein a controller (3) estimates a discharge temperature of the compressor (5) on the basis of a correlation of respective pressure loading characteristics for the detected temperature of the inverter (7), for the rotational speed of the compressor (5), and for the motive force of the compressor (5) in a refrigerating cycle (2).

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 refrigeration cycle apparatus controller includes an expansion-valve controller configured to output an opening-degree command for an expansion valve based on a deviation between a discharge temperature of refrigerant discharged from a compressor and a set discharge temperature, and at least two control parameters including a proportionality coefficient and an integral coefficient, a flow-rate-correction-coefficient calculator configured to calculate a flow-rate correction coefficient from a refrigerant flow rate of refrigerant circulating through a refrigerant circuit and a preset flow-rate reference value, and a coefficient corrector configured to calculate the proportionality coefficient by correcting a preset proportionality-coefficient reference value based on the flow-rate correction coefficient, and calculate the integral coefficient by correcting a preset integral-coefficient reference value based on the flow-rate correction coefficient. The proportionality coefficient and the integral coefficient are calculated such that a variation range of the integral coefficient rate is larger than a variation range of the proportionality coefficient.

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.

An air conditioner has a refrigerant circuit filled with a predetermined amount of a refrigerant, the circuit being formed of an outdoor unit and an indoor unit connected to each other by refrigerant piping, the outdoor unit having a compressor, an outdoor heat exchanger, and an expansion valve, the indoor unit having an indoor heat exchanger. The conditioner has an estimation model that estimates an amount of remaining refrigerant remaining in the circuit by using at least rotation frequency of the compressor, refrigerant discharge temperature at the compressor, heat exchanger temperature, degree of opening of the expansion valve, and outside air temperature, of operation state quantities indicating operation states during operation. The indoor heat exchanger has a sensor that is provided at an indoor heat exchanger intermediate portion connecting a first indoor heat exchanger port and a second indoor heat exchanger port to each other.

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.

Provided are a control method and apparatus for increasing the amount of a circulating refrigerant, and an air conditioner. The control method includes: when a refrigerating capacity need is equivalent to a heating capacity need in the operation of an air-conditioning system, determining whether the discharge temperature of a compressor is greater than a preset safety alert value; if the discharge temperature of the compressor is greater than the safety alert value, adjusting the frequency of a fan of an outdoor heat exchanger; and when the discharge temperature of the compressor is not greater than the safety alert value, controlling to stop the adjustment of the frequency of the fan, and maintaining the air-conditioning system to operate at the adjusted current frequency of the fan.

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.