In an embodiment, a method of preventing evaporator coil freeze in a heating, ventilation and air conditioning (HVAC) system is performed by a controller in the HVAC system. The method includes determining a reference saturated suction temperature (SST) via a sensor disposed in relation to an evaporator coil in the HVAC system. The method also includes determining whether the reference SST is below a minimum SST threshold. The method also includes, responsive to a determination that the reference SST is below the minimum SST threshold, increasing a discharge air temperature (DAT) setpoint.

An HVAC system having a fixed orifice expansion device coupled to an evaporator coil is provided. In one embodiment, an expansion device coupled to an evaporator coil includes a flow restrictor and an evaporator inlet manifold. The flow restrictor includes multiple fixed orifices aligned with the refrigerant distribution tubes to restrict flow of refrigerant from the evaporator inlet manifold into the refrigerant distribution tubes through the multiple fixed orifices. Additional systems, devices, and methods are also disclosed.

A heat exchanger includes plural heat transfer tubes disposed with a specified spacing from each other in the up and down direction, and a distributor configured to distribute refrigerant to the heat transfer tubes. The distributor includes a body part, and plural flow-splitting parts, the body part including a first passage in which refrigerant flows upward, the flow-splitting parts communicating with the first passage and with one of the heat transfer tubes. The flow-splitting parts include one or more first flow-splitting parts each communicating with a first heat transfer tube, which is a higher positioned heat transfer tube. The flow-splitting parts include one or more second heat transfer tubes each communicating with a second heat transfer tube positioned below the first heat transfer tube. The refrigerant inlet of the first flow-splitting part communicates with the first passage at a location below the refrigerant inlet of the second flow-splitting part.

A heat exchanger includes: a gas-refrigerant pipe; a header connected to the gas-refrigerant pipe; and heat transfer tubes connected to the header. The header includes: a first plate member; and a second plate member that is stacked on the first plate member in a plate-thickness direction. The first plate member includes a first opening that constitutes an internal space of the header. The second plate member includes a second opening that, together with the first opening, constitutes the internal space of the header. The internal space of the header communicates with the heat transfer tubes. A first direction is perpendicular to both the plate-thickness direction and a direction in which the heat transfer tubes are arranged. A width of a part of the first opening in the first direction is different from a width of the second opening in the first direction.

Disclosed is a swirl generator for an evaporator, having: a body that extends along a body-center axis between opposing inlet and outlet ends, and includes: a fluid inlet at the inlet end; an outer surface that, at that the outlet end, defines an outlet region with a curved outer boundary forming a convex curve that extends radially inward from an outer diameter surface of the body to an outer axial surface of the body; a center passage formed within the body that extends from the inlet towards the outlet along the body-center axis; and a swirl passage formed at the outlet end of the body, the swirl passage extending between the center passage and the curved outer boundary along a swirl passage axis, whereby a fluid entering from the inlet exits the body at the curved outer boundary, the swirl passage axis forming an acute angle with the body-center axis.

A refrigeration system has: (a) a fluid tight circulation loop including a compressor, a condenser and an evaporator, the evaporator having at least three evaporator zones, each evaporator zone having an inlet port, the circulation loop being further configured to measure the condition of the refrigerant with a refrigerant condition sensor disposed within the evaporator upstream of the evaporator outlet port; and control the flow of refrigerant to the evaporator based upon the measured condition of the refrigerant within the evaporator, and (b) a controller for controlling the flow rate of refrigerant to the evaporator based upon the measured condition of the refrigerant within the evaporator upstream of the evaporator outlet port.

Disclosed is an evaporator header insert, including: a header insert body that extends along a body center axis between body inlet and outlet ends, a center passage located within the header insert body, the center passage extending from the body inlet end to the body outlet end along the body center axis, the center passage surface defining: a center passage inlet portion at the body inlet end; a center passage outlet portion, at the body outlet end, that defines a body nozzle portion on the body center axis, wherein the body nozzle portion has a convergent-divergent shape so that the body nozzle portion has a convergent segment, a divergent segment and a neck segment therebetween; and a conical tip member, fixed to the body outlet end and disposed at least partially within the divergent segment of the body nozzle portion so that a conical outlet passage is formed therebetween.

A thermal management system is described. The thermal management system includes an open circuit refrigeration circuit that has a refrigerant fluid flow path, with the refrigerant fluid flow path including a receiver configured to store a refrigerant fluid, an ejector having a primary flow inlet configured to receive refrigerant, a liquid separator, an evaporator configured to extract heat from a heat load that contacts the evaporator, with the evaporator coupled to the ejector and the liquid separator, and an exhaust line coupled to a vapor side outlet of the liquid separator. In operation, the evaporator in the open circuit refrigeration circuit would be coupled to a heat load.

A thermal management system is described. The thermal management system includes an open circuit refrigeration circuit that has a refrigerant fluid flow path, with the refrigerant fluid flow path including a receiver configured to store a refrigerant fluid, an ejector having a primary flow inlet configured to receive refrigerant, a liquid separator, an evaporator configured to extract heat from a heat load that contacts the evaporator, with the evaporator coupled to the ejector and the liquid separator, and an exhaust line coupled to a vapor side outlet of the liquid separator. In operation, the evaporator in the open circuit refrigeration circuit would be coupled to a heat load.

An evaporator includes an inlet in a lower manifold, an outlet in an upper manifold, and a multiport tube extending between the lower manifold and the upper manifold. The multiport tube provides a flow path between the lower manifold and the upper manifold. One of the outer side walls of the multiport tube is provided with a first evaporator section with a first heat receiving surface and a second evaporator section with a second heat receiving surface, the first and second evaporator sections passing a heat load received via the respective first and second heat receiving surfaces to a fluid in said multiport tube. The first and second heat receiving surfaces form an angle with each other to align with and contact different surfaces of an object to be cooled.