A heat pump apparatus includes: a refrigerant circuit which circulates refrigerant; a heat medium circuit which makes a heat medium flow; a heat exchanger which cause heat exchange to be performed between the refrigerant and the heat medium; and an indoor unit which houses at least the heat exchanger. The heat exchanger has a double-wall structure. The indoor unit includes a container which houses the heat exchanger. In the container, a first opening port is formed to communicate with an outdoor space without communicating with an indoor space.

An air conditioning apparatus includes a refrigerant circuit and a controller. The refrigerant circuit is configured to allow refrigerant to circulate through a compressor, a condenser, an LEV, and an evaporator. The LEV has an opening degree variable from a lower limit opening degree to an upper limit opening degree. The controller is configured to control the LEV to alternately repeat a first opening degree and a second opening degree in a range of less than or equal to a quarter of the upper limit opening degree, the second opening degree being smaller than the first opening degree.

A performance degradation diagnosis system includes a determining unit, and control unit. A refrigeration cycle apparatus includes a refrigerant circuit having a compressor, heat-source-side heat exchanger, and use-side heat exchanger. The determining unit determines, based on an index indicating an operation state of the refrigeration cycle apparatus, performance degradation of the refrigeration cycle apparatus with respect to each of a plurality of performance degradation factors. In a case in which the determining unit determines performance degradation, the control unit grasps an operation condition of the refrigeration cycle apparatus which is operating. In a case in which the operation condition of the refrigeration cycle apparatus is not suitable to determine performance degradation with respect to a performance degradation factor of a determination target, the control unit controls the operation condition of the refrigeration cycle apparatus so that the operation condition of the refrigeration cycle apparatus becomes an appropriate operation condition.

A multiple-circuit heating and cooling system includes a first refrigeration circuit having a first condenser and a first evaporator and a second refrigeration circuit having a second condenser and a second evaporator. The first condenser and the second condenser are arranged in a first row split configuration, and the second condenser is downstream of the first condenser relative to a first air flow directed across the second condenser and the first condenser. Additionally, the first evaporator and the second evaporator are arranged in a second row split configuration, and the first evaporator is downstream of the second evaporator relative to a second air flow directed across the first evaporator and the second evaporator.

An HVAC system with an integrated source of outdoor air is provided. In one embodiment, an HVAC system includes an outdoor unit, having a compressor and a heat exchanger, and a ventilation unit to receive and provide outdoor air to a structure. The ventilation unit has a blower, a dehumidifying coil, and a reheat coil installed in a housing. The HVAC system also includes a first electronic expansion valve coupled outside the housing of the ventilation unit to control refrigerant flow into the dehumidifying coil and a second electronic expansion valve coupled outside the housing of the ventilation unit to control refrigerant flow into the reheat coil. An electronic expansion valve controller is connected to control operation of the first electronic expansion valve and the second electronic expansion valve. Additional systems, devices, and methods are also disclosed.

A vehicle air-conditioning apparatus is provided which is capable of expanding an effective range of a dehumidifying and heating mode to achieve comfortable vehicle interior air conditioning. A control device (controller) executes a dehumidifying and heating mode to let a refrigerant discharged from a compressor 2 radiate heat in a radiator 4, let a part of the refrigerant flow from a bypass circuit (refrigerant pipe 13F) to an indoor expansion valve 8, and let the residual refrigerant flow through an outdoor expansion valve 6. In the dehumidifying and heating mode, the control device has a state of controlling the operation of the compressor 2, based on a heat absorber temperature Te and executes a radiator temperature priority mode which enlarges a capability of the compressor when heat radiation in the radiator is insufficient.

A method for controlling a fan (6) of a vapour compression system (1) is disclosed, the fan (6) being arranged to provide a secondary fluid flow across a heat rejecting heat exchanger (3). A temperature difference, T=T.sub.outT.sub.amb, between a temperature, T.sub.out, of refrigerant leaving the heat rejecting heat exchanger (3) and a temperature, T.sub.amb, of ambient air of the heat rejecting heat exchanger (3) is established. A setpoint value, T.sub.setp, for the temperature difference, T, is obtained, the setpoint value, T.sub.setp, being dependent on the fan speed of the fan (6) in such a manner that the setpoint value, T.sub.setp, increases as the fan speed increases. The fan speed of the fan (6) is controlled in order to control the temperature difference, T, in accordance with the obtained setpoint value, T.sub.setp.

A heating mode control method of an air conditioner, comprises: obtaining an indoor temperature and calculating the difference between the indoor temperature and an indoor target temperature to obtain an indoor temperature difference as air conditioner running at heating mode; performing a coil temperature control process as the indoor temperature difference in a set indoor temperature difference range, wherein the coil temperature control process including: obtaining an indoor coil temperature and controlling the frequency of the compressor according to the indoor coil temperature and a coil target temperature. The application of the method can achieve the purpose of improving the heating effect by increasing the outlet air temperature, thus improving the heating performance of an air-conditioner.

An air conditioner and a method for controlling an air conditioner are provided that efficiently inject a refrigerant into a compressor. The air conditioner may include a compressor to compress a refrigerant; a condenser to condense the refrigerant compressed at the compressor; an evaporator to evaporate the refrigerant condensed at the condenser; and an injection module to selectively or simultaneously inject some or a portion of the refrigerant flowing from the condenser to the evaporator into a high pressure side and a low pressure side of the compressor.

There is disclosed a vehicle air conditioning device of a heat pump system which delays proceeding of frosting onto an outdoor heat exchanger, thereby eliminating or inhibiting deterioration of a heating capability due to the frosting. The vehicle air conditioning device executes a heating mode in which a controller lets a refrigerant discharged from a compressor 2 radiate heat in a radiator 4, decompresses the refrigerant by which heat has been radiated, and then lets the refrigerant absorb heat in an outdoor heat exchanger 7, and on the basis of a difference TXO=(TXObaseTXO) between a refrigerant evaporation temperature TXObase of the outdoor heat exchanger 7 in non-frosting and a refrigerant evaporation temperature TXO of the outdoor heat exchanger 7, the controller corrects a target subcool degree TGSC that is a target value of a subcool degree of the refrigerant in the radiator 4 in an increasing direction in accordance with increase of the difference TXO.