Abstract: A multiple pass, parallel tube heat exchanger with a collection header extending along the length of each of a first and second pass, is provided with a bypass tube which fluidly interconnects the downstream end of the collection header to a midpoint thereof, near the end of the first pass tubes and the beginning of the second pass tubes so as to enhance the flow distribution of two-phase refrigerant from the collection header to the second pass tubes. The distribution flow is further enhanced by the insertion of an eductor nozzle within the collection header, and with the inlet of the eductor nozzle being supplied by refrigerant flow from the condenser to thereby provide a motive flow of two-phase refrigerant in the loop which includes the latter half of the collection header and the bypass tubes.

Abstract: A brazed plate heat exchanger has a two-phase refrigerant flow distribution system with improved circulation features. The inlet manifold has parallel pass conduits interconnected by way of a return bend, with the downstream end of the second pass conduit fluidly interconnected with the upstream end of the first pass conduit to complete the circuit. The manifold first pass conduit has a plurality of outlets formed in its wall to accommodate the flow of two-phase refrigerant to refrigerant channels along its length. A nozzle at the upstream end of the first pass conduit provides a relatively high velocity jet stream of refrigerant flow that propels the flow of refrigerant around the circuit so as to prevent stratification.

Abstract: A falling evaporator has a two-phase refrigerant flow distribution system with improved circulation features in both the header and subheader of the system. Both the header and the subheader have vertically disposed, parallel pass conduits interconnected by way of a return bend, with the downstream end of the second pass conduits then fluidly interconnected with the upstream end of the first pass conduits to complete the circuit. A nozzle at the upstream end of the first pass conduits provides a relatively high velocity jet stream of refrigerant flow that propels the flow of refrigerant around the circuit so as to prevent stratification. The header has a plurality of outlets formed in its wall to accommodate the flow of two-phase refrigerant to the various subheaders, and each subheader has openings formed in a lower wall of its first pass conduit such that refrigerant can flow from the openings, to the outer upper surface of the second pass conduits and eventually to the heat transfer tubes below.

Abstract: A multiple circuit shell and tube heat exchanger exchanges heat between a heat transfer fluid and refrigerant. The first portion of the heat transfer fluid flow enters a first refrigerant circuit and exchanges heat with refrigerant in the first circuit. The second portion of the heat transfer fluid flow then enters a second refrigerant circuit and exchanges heat with refrigerant in the second circuit. By employing a single heat transfer fluid pass, the average leaving temperature difference from each circuit can be reduced, reducing entropy generation and making the system more thermodynamically efficient.

Abstract: A multiple circuit plate heat exchanger exchanges heat between a heat transfer fluid and refrigerant. The first portion of the heat transfer fluid flow enters a first refrigerant circuit and exchanges heat with refrigerant in the first circuit. The second portion of the heat transfer fluid flow then enters a second refrigerant circuit and exchanges heat with refrigerant in the second circuit. By employing a single heat transfer fluid pass, the average leaving temperature difference from each circuit can be reduced, reducing entropy generation and making the system more thermodynamically efficient.

Abstract: A multiple circuit shell and tube heat exchanger exchanges heat between a heat transfer fluid and refrigerant. The first portion of the heat transfer fluid flow enters a first refrigerant circuit and exchanges heat with refrigerant in the first circuit. The second portion of the heat transfer fluid flow then enters a second refrigerant circuit and exchanges heat with refrigerant in the second circuit. By employing a single heat transfer fluid pass, the average leaving temperature difference from each circuit can be reduced, reducing entropy generation and making the system more thermodynamically efficient.

Abstract: A multiple circuit plate heat exchanger exchanges heat between a heat transfer fluid and refrigerant. The first portion of the heat transfer fluid flow enters a first refrigerant circuit and exchanges heat with refrigerant in the first circuit. The second portion of the heat transfer fluid flow then enters a second refrigerant circuit and exchanges heat with refrigerant in the second circuit. By employing a single heat transfer fluid pass, the average leaving temperature difference from each circuit can be reduced, reducing entropy generation and making the system more thermodynamically efficient.

Abstract: An absorption provided with a refrigerant management method and apparatus for temporarily storing liquid refrigerant during cooling mode operation and releasing refrigerant to the evaporator sump as needed to prevent refrigerant pump cavitation during periods of part load operation and causing dilution of solution in the absorber when the system is shut down. The refrigerant is stored in a tank located in the evaporator, with the tank fluidly communicating with the evaporator sump both by way of a side opening in the tank and by way of overflowing the tank. Refrigerant replenishment to the tank occurs during normal operation either by refrigerant flow from the condenser or by way of a bleed line from the refrigerant pump.

Abstract: A refrigerant control apparatus for use in an absorption heating and cooling system of the type which uses a refrigerant and an absorbent, and which includes a generator, a condenser, an absorber and an evaporator having an evaporator sump. The control apparatus includes a reservoir, disposed in condensate collecting relationship to the condenser, and in refrigerant draining relationship to the evaporator. The reservoir has a storage capacity sufficient to store, during operation in the cooling mode, a quantity of refrigerant large enough to reduce the steady state concentration of the operating solution from a first, relatively high concentration used in the cooling mode to a second, relatively low concentration used the heating mode, and includes an overflow structure that allows refrigerant to overflow into the evaporator when the reservoir is filled.

Abstract: A dilution control apparatus for use in an absorption cooling system of the type which uses a refrigerant and an absorbent, and which includes a generator, a condenser having a condenser sump, an absorber having an absorber sump, and an evaporator having an evaporator sump. At least one refrigerant reservoir is arranged to receive refrigerant condensing within the condenser, and to store a quantity of refrigerant which, if released into the system during the dilution phase of the system shutdown process, is sufficient to lower the concentration of the refrigerant-absorbent solution to a concentration low enough to prevent crystals from forming in the absorber after the shutdown process has been completed. Refrigerant is released from the at least one refrigerant reservoir to the evaporator sump at a variable rate, through a first refrigerant releasing path, when the system operates under a cooling load that fluctuates with time.