Integrated hybrid thermostatic expansion valve and method for providing uniform cooling of heat generating devices

Abstract

An apparatus and method are disclosed for ensuring adequate and uniform cooling for any heat-generating device that experiences large heat pulses by integrating parallel expansion devices and their control directly into each of a discrete cooling load or cold plate. One of the parallel expansion devices is an integrated cartridge thermostatic expansion valve (TXV) and the other is an electrically-actuated valve. The TXV is positioned such that a sensing element is located directly within an exit refrigerant stream, thereby improving time-response of the valve and eliminating the need for a capillary tube. The electrically-actuated valve provides a sudden burst of refrigerant while the TXV is responding to sudden heat pulses and operates at the command of the heat generating system or triggered by a temperature rise. The disclosed operational method leads to an order of magnitude reduction in settling time after a heat pulse.

Claims

1. A valve assembly for supplying a refrigerant flowrate to at least one cold plate in a vapor compression system, comprising: a housing having a bifurcated passageway having a first flow path and a second flow path, an intermediate passage, a first orifice between the intermediate passage and the second flow path of the bifurcated passageway, a first annular volume oriented with the first flow path in the bifurcated passageway, and a second annular volume oriented with the intermediate passage; an expansion valve in the housing and positioned within the first annular volume and second annular volume; an electrically-actuated valve in the housing and positioned between the second flow path of the bifurcated passageway and the intermediate passage; and wherein the first orifice and the electrically-actuated valve are sized such that the refrigerant flowrate through the intermediate passage is 1.5 to 3 times more than the flowrate through the first flow path in the bifurcated passageway.

2. The valve assembly of claim 1, wherein the first orifice and the electrically-actuated valve are sized such that the refrigerant flowrate through intermediate passage is 1.9 times more than the flowrate through the second flow path in the bifurcated passageway.

3. The valve assembly of claim 1, wherein the expansion valve is a feedback-controlled expansion valve operatively arranged so that an expandable bulb thereof is located directly within an exit refrigerant stream of the at least one cold plate.

4. The valve assembly of claim 3, wherein the feedback-controlled expansion valve is a thermal expansion valve and the expandable bulb is a temperature-sensitive feedback expandable bulb located directly within the exit refrigerant stream of the at least one cold plate.

5. The valve assembly of claim 1, wherein the electrically-actuated valve operates in one of only a full-open position and only a full-closed position.

6. The valve assembly of claim 5, wherein the electrically-actuated valve is selected from the group consisting of a solenoid valve, a rapidly-actuating gate valve, and a butterfly valve.

7. The valve assembly of claim 1, wherein the expansion valve is a thermostatic expansion valve, and the electrically-actuated valve is configured to remain closed during low heat loads so that liquid refrigerant flows only through the first flow path in the bifurcated passageway.

8. The valve assembly of claim 1, wherein a partial boss is arranged in a cavity between the electrically-actuated valve and the first orifice to ensure that the first orifice ingests a liquid portion of two-phase refrigerant flow from the electrically-actuated valve.

9. The valve assembly of claim 8, wherein the two-phase refrigerant flow expands through the intermediate passage and into the second annular volume to a first port fluidly connected to the second annular volume.

10. The valve assembly of claim 1, further comprising: the expansion valve having a needle, needle seat, and a plurality of holes for fluidly connecting the first annular volume and the second annular volume; wherein the needle and needle seat define a second orifice; an expandable bulb in contact with the needle; and wherein a movement of the expandable bulb moves the needle from the needle seat to create a space in the second orifice for expanded refrigerant to pass through the second orifice and to discharge from the plurality of holes into the second annular volume.

11. The valve assembly of claim 10, wherein the expanded refrigerant from the second annular volume enters a first port in fluid connection with the second annular volume.

12. The valve assembly of claim 11, further comprising: a second port in the housing to receive superheated vapor refrigerant from at least one cold plate; and wherein the expandable bulb is a temperature-sensitive feedback expandable bulb located in the housing and positioned adjacent the second port such that the superheated vapor refrigerant flows over the temperature-sensing element.

13. The valve assembly of claim 12, wherein the temperature-sensitive feedback expandable bulb is positioned adjacent the needle and, in response to the superheated vapor, axially moves the needle from the needle seat so that the expanded refrigerant in the first annular volume passes through the second orifice and discharges from the plurality of holes into the second annular volume.

14. The valve assembly of claim 1, wherein the expansion valve is a thermal expansion valve having a superheat adjustment module to allow for the adjustment of superheat during operation of the thermal expansion valve, and the housing has a partial hexagonal shape configured to interface with a hexagonal portion of superheat adjustment module of the thermostatic expansion valve in order to prevent the thermal expansion valve from rotating within the housing and to allow for adjustment of the thermostatic expansion valve during vapor compression system operation without having to remove the thermal expansion valve.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) These and other features, aspects, and advantages of the present invention will become better understood with regard to the following description, appended claims, and accompanying drawings where:

(2) FIG. 1 is a cross-sectional view of the integrated TXV cartridge shown in U.S. Pat. No. 9,398,722.

(3) FIG. 2 is perspective view of one currently contemplated embodiment of the present invention.

(4) FIG. 3 is a cross-sectional view along line 3-3 of the embodiment shown in FIG. 2.

(5) FIG. 4 is a detail view of the needle and needle seat area shown in FIG. 3.

(6) FIG. 5 is a side view of the embodiment shown in FIGS. 2 and 3 with secondary electrically-actuated valve and superheat adjustment cap removed.

(7) FIG. 6 is a cross-sectional view along line 6-6 of FIG. 5 through the precision orifice.

(8) FIGS. 7A and 7B are, respectively, schematic diagrams of the hybrid valve assembly of the present invention using a mechanically passive expansion device such as orifice plates or capillary tubes associated with the evaporator of a conventional vapor control system and a feedback-controlled expansion devices such as evaporator-exit controlled TXVs and EXVs and float expansion valves that can utilize evaporator or condenser conditions, e.g. the liquid level in the evaporator or condenser.

(9) FIGS. 8A and 8B are, respectively, perspective views of the integrated hybrid valve assembly of the present invention showing the assembly directly connected with the cold plate and the assembly joined to the cold plate via tubing or the like.

DESCRIPTION

(10) In the Summary above and the Description, and the claims below, and in the accompany drawings, reference is made to particular features (including method steps) of the invention. It is to be understood that the disclosure of the invention in this specification includes all possible combinations of such particular features. For example, where a particular aspect or embodiment of the invention, or a particular claim, that feature can also be used, to the extent possible, in combination with and/or in the context of the other particular aspects and embodiments of the invention, and in the invention generally.

(11) The integrated hybrid TXV of the present invention designated generally by numeral (101) in FIG. 2 is integrated directly into either a separate housing (104) or directly into a port in the vapor compression system cold plate (501) as seen in FIG. 8A and is coupled with a secondary electrically-actuated valve shown in detail in FIG. 3 and described below. Two copper interface tubes are brazed into the housing (104), namely a first smaller tube (102) that functions as a subcooled liquid inlet from the condenser of a vapor compression system and a second large tube (103) that functions as an outlet to return superheated vapor to the compressor of the vapor compression system. The copper interface tubes (102), (103) allow for conventional refrigeration braze joints, compression fittings, O-ring seal fittings, and other conventional tube attachment and sealing techniques routinely used in industry. While our currently preferred embodiment incorporates this integrated hybrid TXV into the cold plate, the integrated hybrid TXV can also be located external to the cold plate or evaporative heat exchanger as shown in FIG. 8B and connected to the cold plate or evaporative heat exchanger with tubing (502). The material of the housing (104) in the current embodiment is aluminum with a composition that facilitates controlled atmosphere or vacuum brazing in order to be secured to a cold plate, for example, see FIG. 8A. The housing (104) has an interface (105) with the cold plate geometry in which contain two differently-sized fluid ports (107), (109) and two locational dowel pins (106). The dowel pins (106) are dissimilar in size and asymmetric in orientation to prevent incorrect installation of the housing (104) to a cold plate. The first smaller port (107) supplies the cold plate with two-phase refrigerant from the integrated TXV and a secondary electrically-actuated valve (108), and the second larger port (109) receives superheated vapor refrigerant from the cold plate. The interface (105) between the housing (104) and the cold plate (501) is designed to be a control-atmosphere or vacuum brazed joint in our currently preferred embodiment. While this is our preferred manner of fabrication and assembly, one skilled in the art will understand that there a number of other ways of fabricating and assembling our disclosed invention.

(12) In the currently preferred embodiment, a compact, cartridge-like electrically-actuated valve (108) is placed in parallel with a cartridge-like integrated TXV (202) as seen in FIG. 3. High-pressure liquid refrigerant enters the assembly through the first smaller tube (102) and flows through a bifurcated passageway (201). The liquid is split as shown by arrows A, B and flows in parallel to the integrated TXV (202) and the secondary electrically-actuated valve (108). Between the bifurcated passageway (201) and the integrated TXV (202) is a first annular volume (203) from which the integrated TXV (202) draws. The annular volume (203) enables valve operation to be insensitive to rotational placement of the integrated TXV (202). Once refrigerant enters the integrated TXV (202) from the first annular volume (203), the refrigerant is expanded through the orifice (301) created by the space between the needle (204) and needle seat (205) as seen in the detail view of FIG. 4. Referring to both FIGS. 3 and 4, the orifice (301) size, and therefore the refrigerant flow rate, is determined by the needle (204) motion that is controlled by the expansion or contraction of a temperature-sensitive feedback expandable bulb, such as, the bellows (206) as it responds to sensed superheat, and a mechanical spring (303) whose initial deformation is controlled by the superheat adjustment module (207) as is well understood in the art. The superheat adjustment module (207) is protected against the environment by a superheat adjustment cap (208) and an environmental seal (209). The superheat adjustment cap (208) can be electroplated with zinc to be galvanically similar to the aluminum housing (104).

(13) The expanded refrigerant from the orifice (301) by way of flow path A is discharged through a plurality of holes (302) to a second annular volume (210). In parallel to flow path A, some of the flow may be permitted to flow through the electrically-actuated valve (108) by way of flow path B. High-pressure liquid refrigerant in flow path B is expanded through the secondary electrically-actuated valve (108) when opened and is eventually also discharged into the second annular volume (210) by way of an intermediate passage (211). The refrigerant from the second annular volume (210) which is a combination of flow path A and flow path B is then passed to the cold plate via the first port (107) by way of flow path C. The refrigerant is evaporated by heat added to the cold plate and returns to the housing (104) via the second port (109) where it flows around the bellows (206). The bellows has been designed to expand or contract in only in the axial direction, so as to move the needle (204) in relation to the needle seat (205). The bellows (206) responds (expands or contracts) to the temperature and pressure in the cold plate exhaust stream and the movement of the bellows thereby moves the needle (204) accordingly. Finally, the refrigerant then leaves the housing (104) via the second large tube (103). In general, the electrically-actuated valve (108) would only be opened in the event of a sudden increase in heat load or to equalize pressure upon system shut-down to reduce the startup load on the compressor (since restarting the compressor against a pressure differential would increase the load and current draw of the compressor).

(14) FIG. 5 shows the left side of the integrated hybrid TXV assembly (101) with the superheat cap (208) and the secondary electrically-actuated valve (108) removed. FIG. 6, which is a detail 6-6 of FIG. 5, shows a circular, sharp-edged or precision plain orifice (401) that is placed in series with the electrically-actuated valve (108) to achieve the desired range of flow in this flow path. As pointed out earlier, the geometry and components in the electrically-actuated valve flow path, including the precision plain orifice (401) and the electrically-actuated valve (108) are both sized for a flowrate for a given pressure loss such that they working together to supply between 1.5 to 3 times, preferably 1.9 times, the flowrate of the integrated TXV when the electrically-actuated valve is opened. Additionally, the ratio of flow between the two flow paths, A and B, is controlled by the relative size of the precision plain orifice (401) and the needle (204). The precision orifice (401) receives expanded refrigerant from the secondary electrically-actuated valve (108) and is positioned such that it intersects with an intermediate passage (211) that is coaxial with the first port (107) and is connected to the second annual volume (210). A partial boss (402) is provided at the bottom of the otherwise circular cavity between the secondary electrically-actuated valve (108) and the precision plain orifice (401) to ensure that the precision plain orifice (401) ingests the liquid portion of the two-phase flow from the secondary electrically-actuated valve (108).

(15) FIGS. 3 and 5 also shows the unique mechanical securing of the integrated TXV (202). The integrated TXV (202) may need to be field-adjustable, and this entails turning the superheat adjustment screw (212). It is preferable to adjust the superheat adjustment screw (212) with the integrated TXV (202) already having been placed in the housing (104) so the vapor compression system seal can remain intact to avoid costly refrigerant recovery and charging procedures and to allow the superheat to be adjusted during operation. To accomplish this, a partially hexagonal feature (303) is machined into the housing to approximate the hexagonal shape of the superheat adjustment module (207). Shims (304) are placed in the void between the hexagonal portion of the superheat adjustment module (207) and the partially hexagonal feature (303) in the housing (104) that act as a rotational mechanical stop for the integrated TXV (202) that prevents rotation. Thus, the superheat adjustment screw can be turned relative to the integrated TXV (necessary to field adjust the superheat) without removing the integrated TXV from the housing and losing refrigerant charge. One or more axial retention mechanisms or fasteners such as internal rings or snap rings, or may be C-clip may be used between the superheat adjustment module and a cap to provide an axial mechanical stop for the integrated TXV in the housing. The arrangement of cap, C-clip, and integrated TXV allows the entirety of the integrated TXV to be environmentally protected during operation while also allowing for the superheat to be adjusted in place when not operating.

(16) In summary, the integrated hybrid TXV according to the present invention provides faster time response and more precise thermal control than integrated TXVs alone, allows for field adjustment of the integrated TXV without breaking the vapor compression system seal, and provides a more compact and higher performance solution in comparison to conventional expansion valve alone.

(17) While a currently preferred embodiment of the invention has been illustrated and described, it should be understood that, after reading this disclosure, variations to this embodiment will be apparent to one skilled in the art without departing from the principles of the invention described herein. For example, one skilled in the art will now understand that an electrically-actuated expansion valve (EXV), capillary tube expansion device, orifice plate expansion device or any other type of throttling valve could be used in parallel with the electrically-actuated valve as shown in FIGS. 7A and 7B. Likewise, the single housing (101) can be integrated with the cold plate (501) or joined therewith by tubing (502) as shown, respectively, in FIGS. 8A and 8B.

(18) While we have shown and described several embodiments in accordance with our invention, it should be understood that the same is susceptible to further changes and modifications without departing from the scope of our invention. Therefore, we do not want to be limited to the details shown and described herein but intend to cover all such changes and modifications as are encompassed by the scope of the appended claims.