Evaporator having a hybrid expansion device for improved aliquoting of refrigerant

Patent metadata

Field	Value
Publication number	US-9568225-B2
Application number	US-201314069878-A
Country	US
Kind code	B2
Filing date	Nov 1, 2013
Priority date	Nov 1, 2013
Publication date	Feb 14, 2017
Grant date	Feb 14, 2017

Abstract

An automotive evaporator heat exchanger is provided having a hybrid expansion device configured to aliquot refrigerant across the refrigerant tubes. The hybrid expansion device includes a first stage refrigerant pressure drop device and a second stage refrigerant pressure drop device. The first stage refrigerant pressure drop device is a TXV configured to receive and expand a liquid phase refrigerant into a first mixture of two phase refrigerant and the second stage refrigerant pressure drop device is a tube extending within the inlet manifold configured to expand the first mixture of two phase refrigerant into a second mixture of two phase refrigerant. The tube includes a plurality of orifices and a tube diameter large enough to prevent resistance to refrigerant flow, but, small enough to prevent the first mixture of two phase refrigerant flow from separating into liquid and vapor strata.

First claim

Having described the invention, it is claimed:

1. An automotive evaporator heat exchanger comprising:
an inlet manifold defining an interior chamber extending along a horizontal manifold axis;
a plurality of refrigerant tubes, each having an open end extending into the interior chamber from an underside of the inlet manifold,
a first stage refrigerant pressure drop device configured to receive and expand a liquid phase refrigerant into a first mixture of two phase refrigerant;
a second stage refrigerant pressure drop device disposed in the interior chamber and configured to receive and expand the first mixture of two phase refrigerant into a second mixture of two phase refrigerant and aliquot the second mixture of two phase refrigerant to the open ends of the plurality of refrigerant tubes, wherein the second stage refrigerant pressure drop device is a pressure-drop tube having a plurality of orifices configured to expand the first mixture of two phase refrigerant into the second mixture of two phase refrigerant; and
an inlet end connector having a first end outside the inlet manifold, receiving an outlet end of the first stage refrigerant pressure drop device, and having a second end inside the inlet manifold, receiving an inlet end of the second stage refrigerant pressure drop device;
wherein the orifices of the second stage refrigerant pressure drop device are oriented opposite to the direction of gravity and away from the refrigerant tubes.

2. The automotive evaporator heat exchanger of claim 1 , wherein the inlet manifold includes the inlet port and a plurality of refrigerant tube slots;
wherein each open end of the plurality of refrigerant tubes extends through a corresponding one of the plurality of tube slots such that the open ends are in hydraulic communication with the interior chamber;
further comprising a hybrid expansion device including the first stage refrigerant pressure drop device and the second stage refrigerant pressure drop device.

3. The automotive evaporator heat exchanger of claim 2 , wherein the first stage refrigerant pressure drop device is located adjacent to the inlet port.

4. The automotive evaporator heat exchanger of claim 3 , wherein the second stage refrigerant pressure drop device is in hydraulic connection downstream of the first stage refrigerant pressure drop device and disposed within the interior chamber.

5. The automotive evaporator heat exchanger of claim 4 , wherein the first stage refrigerant pressure drop device is a thermal expansion valve configured to expand the liquid phase refrigerant into the first mixture of two phase refrigerant having about 75-85% by mass liquid phase.

6. The automotive evaporator heat exchanger of claim 5 , wherein the pressure-drop tube disposed within the interior chamber of the inlet manifold includes a blind distal end opposite that of the inlet end, and the plurality of orifices between the blind distal end and the inlet end;
wherein the pressure-drop tube is configured to retain and accumulate a portion of the liquid phase of the first mixture of two phase refrigerant and expand the first mixture of two phase refrigerant into the second mixture of two phase refrigerant having about 65-75% by mass liquid phase.

7. The automotive evaporator heat exchanger of claim 6 , wherein the plurality of orifices are arranged in a linear array parallel to the inlet manifold.

8. The automotive evaporator heat exchanger of claim 7 , wherein the pressure-drop tube is configured to retain and accumulate the first mixture of two phase refrigerant until a liquid phase of the first mixture of the two phase refrigerant fills the interior volume of the pressure-drop tube before being discharged through the orifices as a second mixture of two phase refrigerant, thereby aliquoting the two-phase refrigerant across the refrigerant tubes.

9. The automotive evaporator heat exchanger of claim 7 , wherein the pressure-drop tube includes a tube diameter defining a cross-sectional area, wherein the pressure-drop tube is sized such that, during operation of the evaporator heat exchanger, the liquid phase of accumulated refrigerant occupies at least 99% of the cross-sectional area beneath the orifices.

10. The automotive evaporator heat exchanger of claim 9 , wherein the pressure-drop tube diameter is small enough to prevent the incoming first mixture of two phase refrigerant flow from separating into a liquid and vapor strata.

11. The automotive evaporator heat exchanger of claim 10 , wherein the pressure-drop tube is configured such that the pressure drop of the flow from the inlet end to the distal end in the axial direction is below 10% of the total pressure drop across the pressure-drop tube at all flow velocities of the two-phase refrigerant.

12. The automotive evaporator heat exchanger of claim 1 , wherein the first stage refrigerant pressure drop device is a thermostatic expansion valve configured to expand the liquid phase refrigerant into the first mixture of the two phase refrigerant having about 75-85% by mass liquid phase.

13. The automotive evaporator heat exchanger of claim 12 , wherein the second stage refrigerant pressure drop device is configured to expand the first mixture of two phase refrigerant into the second mixture of two phase refrigerant having about 65-75% by mass liquid phase.

14. The automotive evaporator heat exchanger of claim 13 , wherein the pressure-drop tube diameter is small enough to prevent the incoming first mixture of two phase refrigerant flow from separating into liquid and vapor strata.

15. The automotive evaporator heat exchanger of claim 14 , wherein the tube diameter is further small enough such that the second mixture of two phase refrigerant occupies at least 99% of the cross-sectional area of the pressure-drop tube.

16. The automotive evaporator heat exchanger of claim 1 ,
wherein the pressure-drop tube is configured to retain and accumulate the first mixture of two phase refrigerant until a liquid phase of the first mixture of two phase refrigerant fills the interior volume of the pressure-drop tube before being discharged through the orifices as a second mixture of two phase refrigerant, thereby aliquoting the refrigerant across the refrigerant tubes.

17. The automotive evaporator heat exchanger of claim 16 , wherein the plurality of orifices are arranged in a linear array parallel to the inlet manifold.

18. The automotive evaporator heat exchanger of claim 16 , wherein the pressure-drop tube includes a tube diameter defining a cross-sectional area, wherein the pressure-drop tube is sized such that, during operation of the evaporator heat exchanger, the liquid phase of the accumulated first mixture of two phase refrigerant occupies at least 99% of the cross-sectional area beneath the orifices of the pressure-drop.

Assignees

• Mahle Int Gmbh

Inventors

• Chowdhury Sourav
• Kadle Prasad Shripad
• Kowsky Carrie M

Classifications

• F28F9/026

  with static flow control means, e.g. with means for uniformly distributing heat exchange media into conduits · CPC title

• F25B39/028 Primary

  having distributing means · CPC title

• F28F9/0273

  with multiple holes · CPC title

• F28F9/027

  in the form of distribution pipes · CPC title

• F25B2341/06

  Details of flow restrictors or expansion valves · CPC title