Dual mode heat exchanger assembly

Abstract

A dual mode heat exchanger has a first and second manifold with a plurality of flow tubes fluidly connecting the manifolds for passing refrigerant between the manifolds. The first manifold is divided into at least two chambers. The second manifold defines a single cavity but can form more than one chamber. Separators divide the cavities and are offset from each other creating groups of flow tubes that connect one chamber in each manifold. At least one port in each chamber of one of the manifolds is in the open position for controlling refrigerant circulation. All of the ports are opened in one of the manifolds to permit refrigerant to pass through all of the plurality of tubes in at least one pass in evaporator mode. At least one of the ports is closed to permit refrigerant to pass through all of the plurality of flow tubes in at least two passes in condenser mode.

Description

BACKGROUND OF THE INVENTION[0001]1. Field of the Invention[0002]The present invention relates to a dual mode heat exchanger assembly and a method of operating the heat exchanger assembly.[0003]2. Description of the Prior Art[0004]Dual mode heat exchanger assemblies operate in a condenser mode for cooling and an evaporator mode for heating. System operating requirements related to refrigerant phase, velocity and distribution vary between the condenser and the evaporator modes. In the evaporator mode, partially expanded two phase refrigerant enters the heat exchanger where the refrigerant continues to expand absorbing heat from the air. Momentum effects due to large mass differences between gas and liquid phase can result in separation of the phases. This two phase flow can result in poor refrigerant distribution in the heat exchanger assembly degrading performance in the evaporator mode and can cause icing / frosting of the core.[0005]Dual mode heat exchanger assemblies and methods of ...

AI Technical Summary

Benefits of technology

[0011]The subject invention provides a heat exchanger assembly having a first manifold and a second manifold each defining a hollow cavity, and in spaced and substantially parallel relationship with each other. A separator is disposed within the first manifold and divides the cavity of the first manifold into a first chamber and a second chamber. A plurality of flow tubes are fluidly connected to the first and second manifolds for passing refrigerant between the manifolds. A plurality of ports are connected to at least one of the first and second manifolds. Each of the ports have an open position for allowing refrigerant to flow into and out of the manifolds and a closed position for preventing refrigerant from flowing into and out of the manifolds. There is at least a first port, a second port, and a third port. An external controller switches the heat exchanger assembly between an evaporator mode and a condenser mode. At least one of the ports in each of the chambers and cavity of one of the manifolds is in the open position for circulating refrigerant through all of the plurality of flow tubes in at least one pass when the heat exchanger assembly is operating in the evaporator mode and at least one of the ports is in the closed position for circulating refrigerant through the plurality of flow tubes in at least two passes when the heat exchanger assembly is operating in the condenser mode.

[0012]The subject invention also provides a method of operating a heat exchanger assembly circulating the refrigerant through all of the plurality of flow tubes in at least one pass in the evaporator mode and in more than one pass in the condenser mode, including the following steps: opening one of the ports in each of the manifolds to define an evaporator mode; introducing refrigerant into one of the manifolds; passing the refrigerant through all of the plurality of tubes in a single pass; exiting the refrigerant from an opposing manifold; closing the third port of the second manifold to define a condenser mode; introducing the refrigerant into one of the chambers of each one of the manifolds to define an inlet chamber; passing the refrigerant through the plurality of tubes connected to the inlet chamber; passing the refrigerant into another chamber of one of the manifolds to define a mid-flow chamber; passing the refrigerant through the plurality of tubes connected to the mid-flow chamber; passing the refrigerant into another chamber of one of the manifolds to define an outlet chamber; and exiting refrigerant through the port connected to the outlet chamber.

[0013]The subject invention also provides a method

Problems solved by technology

Momentum effects due to large mass differences between gas and liquid phase can result in separation of the phases.

This two phase flow can result in poor refrigerant distribution in the heat exchanger assembly degrading performance in the evaporator mode and can cause icing / frosting of the core.

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