A control method and device for an air conditioner outdoor unit, an outdoor unit and an air conditioner are provided. The outdoor unit has a compressor, a first sensor for detecting an air exhaust pressure of the compressor, and a second sensor for detecting an air return pressure of the compressor. According to the method, a target pressure value is determined; an air exhaust pressure value detected by the first sensor or an air return pressure value detected by the second sensor is periodically obtained as a first pressure value; and the frequency of the compressor is adjusted according to the first pressure value and the target pressure value.

A heat exchanger for an air conditioner for which a zeotropic refrigerant mixture is used is obtained, and the heat exchanger, when used as an evaporator, enables reduction of the amount of required refrigerant without deteriorating the heat transfer performance. The heat exchanger includes: a plurality of fins stacked together at predetermined intervals therebetween; first heat transfer pipes which extend through the plurality of fins, in which a heat medium flows, and which have a plurality of grooves in the inner surface of the pipes; and second heat transfer pipes extending through the plurality of fins, having one end connected to one end of the first heat transfer pipes to form one heat medium flow path, being smaller in pipe diameter than the first heat transfer pipes, and having an inner surface shape providing a pressure loss per unit length smaller than that of the first heat transfer pipes.

There is provided a HVAC system comprising: a fluid circuit for conveying a refrigerant; a compressor for compressing the refrigerant; three heat exchangers defining an evaporator, an outdoor exchanger and a heat recovery exchanger provided along the fluid circuit; an expansion valve provided along the fluid circuit; and a receiver connected in parallel to the expansion valve, wherein a fill valve is located between the receiver and a connection upstream of the expansion valve and a drain valve is located between the receiver and a connection downstream of the expansion valve; wherein the fluid circuit comprises a plurality of valves which are configured to be controlled based on a selected operating mode such that at least one of the outdoor exchanger and the heat recovery exchanger is connected to a discharge line of the compressor and in series with one of the other heat exchangers which is connected to a suction line of the compressor, with the expansion valve disposed between the heat exchangers; wherein the fill and drain valves are configured to be controlled to store a volume of refrigerant in the receiver so as to provide an effective refrigerant charge in the fluid circuit that corresponds to the selected operating mode.

There is provided a HVAC system comprising: a fluid circuit for conveying a refrigerant; a compressor for compressing the refrigerant; three heat exchangers defining an evaporator, an outdoor exchanger and a heat recovery exchanger provided along the fluid circuit; an expansion valve provided along the fluid circuit; and a receiver connected in parallel to the expansion valve, wherein a fill valve is located between the receiver and a connection upstream of the expansion valve and a drain valve is located between the receiver and a connection downstream of the expansion valve; wherein the fluid circuit comprises a plurality of valves which are configured to be controlled based on a selected operating mode such that at least one of the outdoor exchanger and the heat recovery exchanger is connected to a discharge line of the compressor and in series with one of the other heat exchangers which is connected to a suction line of the compressor, with the expansion valve disposed between the heat exchangers; wherein the fill and drain valves are configured to be controlled to store a volume of refrigerant in the receiver so as to provide an effective refrigerant charge in the fluid circuit that corresponds to the selected operating mode.

Provided is a refrigerant distributor including: a first space forming portion having a first refrigerant port and a second refrigerant port; and a second space forming portion, which extends laterally from a lower part of the first space forming portion, and has a plurality of heat transfer pipe connecting portions. A gas-liquid refrigerant mixture flows into the first space forming portion through the first refrigerant port. Heat transfer pipes are connected at positions of the plurality of heat transfer pipe connecting portions in the second space forming portion.

A receiver for a heating, air conditioning, and refrigeration system includes a tube extending along a tube axis from a first receiver end to a second receiver end opposite the first receiver end, and a single receiver port. The receiver port is configured as both a receiver inlet and a receiver outlet. A heating, air conditioning, and refrigeration system includes a compressor configured to compress a refrigerant flow, a refrigerant pathway configured to convey the refrigerant flow through the heating, air conditioning, and refrigeration system, and a receiver fluidly connected to the refrigerant pathway. The receiver includes a tube extending along a tube axis from a first receiver end to a second receiver end opposite the first receiver end, and a single receiver port. The receiver port is configured as both a receiver inlet and a receiver outlet, and is connected to the refrigerant pathway via the single receiver port.

A receiver for a heating, air conditioning, and refrigeration system includes a tube extending along a tube axis from a first receiver end to a second receiver end opposite the first receiver end, and a single receiver port. The receiver port is configured as both a receiver inlet and a receiver outlet. A heating, air conditioning, and refrigeration system includes a compressor configured to compress a refrigerant flow, a refrigerant pathway configured to convey the refrigerant flow through the heating, air conditioning, and refrigeration system, and a receiver fluidly connected to the refrigerant pathway. The receiver includes a tube extending along a tube axis from a first receiver end to a second receiver end opposite the first receiver end, and a single receiver port. The receiver port is configured as both a receiver inlet and a receiver outlet, and is connected to the refrigerant pathway via the single receiver port.

Cooler composed by an outer tank, within which a cooling tank and a useful tank are housed, among which there is an array of thermal energy accumulators, and within the tank useful there are temperature compensation chambers.

Cooler composed by an outer tank, within which a cooling tank and a useful tank are housed, among which there is an array of thermal energy accumulators, and within the tank useful there are temperature compensation chambers.

A header includes a plurality of branch tubes and a header manifold. If refrigerant flowing into the header manifold forms a pattern of annular flow or churn flow, tips of the branch tubes inserted into the header manifold pass through a liquid-phase portion having a thickness δ [m] and reach a gas-phase portion. The thickness δ [m] of the liquid-phase portion is defined as δ=G×(1−x)×D/(4ρ.sub.L×U.sub.LS), where G is a flow speed [kg/(m.sup.2 s)] of the refrigerant, x is a quality of the refrigerant, D is an inside diameter [m] of the header manifold, ρ.sub.L is a liquid density [kg/m.sup.3] of the refrigerant, U.sub.LS is a reference apparent liquid speed [m/s] that is a maximum value within a range of variation in an apparent gas speed of the refrigerant flowing into a flow space of the header manifold. The reference apparent liquid speed U.sub.LS [m/s] is defined as G(1−x)/ρ.sub.L.