Field

The disclosure herein relates to a heating, ventilation, and air-conditioning ("HVAC") system, such as a bus HVAC system. Generally, methods, systems, and apparatuses are described that are directed to help evenly distribute refrigerant to, for example, a plurality of evaporators of the HVAC system.

Background

A HVAC system typically includes a compressor to compress refrigerant vapor, a condenser to condense the compressed refrigerant vapor to liquid refrigerant, an expansion device to expand the liquid refrigerant to a two-phase refrigerant liquid/vapor mixture, and an evaporator to help exchange heat between the two-phase refrigerant mixture and, for example, air flowing across the evaporator.

Some HVAC systems, such as some bus HVAC systems or HVAC systems with relatively large capacities, may include a plurality of evaporator units due to, for example, design requirements. The two-phase refrigerant liquid vapor mixture expanded by the expansion device may be directed into a refrigerant distributor and be distributed into each of the evaporator units by the refrigerant distributor.

Summary

Methods, systems and apparatuses are provided to help evenly distribute refrigerant in a HVAC system that may have a plurality of evaporator units. Generally, a refrigerant flow (e.g. a two-phase refrigerant mixture flow) may be firstly directed into an internal chamber of a refrigerant distributor. The refrigerant flow may be directed into the internal chamber of the refrigerant distributor in a direction that is angular to a longitudinal direction of the refrigerant distributor so as to direct the refrigerant flow into a swirl/vortex motion in the internal chamber. A centrifugal force created by the swirl/vortex motion may help form a relatively uniform refrigerant region on an internal surface of the internal chamber. The refrigerant in the relatively uniform refrigerant region may be directed out of the internal chamber into one or more evaporator units.

In some embodiments, the refrigerant, distributor may include a distribution vessel with a cylinder-shaped profile extending in a longitudinal direction. The distribution vessel may have a plurality of distribution outlets that are in fluid communication with the internal chamber of the distribution vessel, in some embodiments, a refrigerant inlet line may be configured to direct refrigerant into the internal chamber of the distribution vessel at a middle region of the distribution vessel. The refrigerant inlet line may have one or more openings positioned inside the internal chamber and may be on a wail of the inlet l ine.

In some embodiments, the opening(s) may be configured to open to a direction that is angular to the longitudinal direction. The opening(s) can be configured to direct a refrigerant flow into the internal chamber from the inlet line. The refrigerant flow directed out of the inlet line initially may have a direction that is angular to the longitudinal direction. The angular refrigerant flow can form a swirl/vortex motion in the internal chamber. The swirl/vortex motion of the refrigerant flow can help create a relatively uniform region of refrigerant on an internal surface of the internal chamber, the majority of which may be liquid refrigerant. Compared to the liquid refrigerant, gaseous refrigerant may stay in a region that, is relatively close to the longitudinal centerline of the internal chamber.

In some embodiments, the inlet line may have a refrigerant flow splitter configured to split the refrigerant flow into one or more refrigerant streams in the inlet line. The one or more refrigerant streams can be directed into the internal chamber at different directions. In some embodiments, the refrigerant flow can be split into two refrigerant streams, a first and a second one of which are directed to a first and a second end of the refrigerant distributor respectively.

In some embodiments, the distributor outlets may be positioned on a body of the distribution vessel. The distributor outlets may be configured to direct refrigerant from the internal chamber to one or more evaporator units of the H VAC system. In some embodiments, the distributor outlets can be configured to direct refrigerant from the relatively uniform refrigerant region formed by the swirl/vortex motion into one or more evaporator units.

In some embodiments, a method of distributing refrigerant may include directing a refrigerant flow into an inlet line, splitting the refrigerant flow into one or more separate refrigerant streams, directing the separate refrigerant streams into a cylinder-shaped internal chamber of a refrigerant distributor at a middle portion of the refrigerant distributor; and creating a swirl/vortex motion in the refrigerant streams along a longitudinal direction of the internal chamber. In some embodiments, refrigerant can be directed from the swirling/vortexing refrigerant streams in the internal chamber into one or more evaporator units.

Other features and aspects of the embodiments will become apparent by consideration of the following detailed description and accompanying drawings.

Brief Description of the Drawings

Reference is now made to the drawings in which like reference numbers represent corresponding parts throughout.

Fig. 1 illustrates a HVAC system that includes a plurality of evaporator units, according to one embodiment.

Figs. 2A to 2G illustrate different aspects of a refrigerant distributor, according to one embodiment. Fig. 2A is a transparent perspective view of the refrigerant, distributor. Fig. 2B is a transparent end view of the refrigerant distributor. Fig. 2C illustrates a transparent perspective view of an inlet, line of the refrigerant distributor. Fig. 2D illustrates an exploded view of the inlet line of Fig. 2C. Fig. 2E illustrates a splitter of the inlet line of Fig. 2C. Fig, 2F is an enlarged view of a portion of the view of Fig. 2C. Fig. 2G is a partial section view along line 2G-2G in Fig. 2C.

Figs. 3 A to 3C illustrate a schematic view of the operation of the refrigerant distributor as shown in Fig. 2A. Fig. 3 A illustrates a schematic view of refrigerant flow directions inside the refrigerant distributor. Fig. 3B illustrates a schematic view of the liquid/gas distribution when a two-phase refrigerant flow is directed into the refrigerant distributor. Fig. 3C is an enlarged view of a portion of the view of Fig. 3 A. Detailed Description

Some HVAC systems, such as some bus HVAC systems or HVAC systems with relatively large capacities, may include more than one evaporator unit. A refrigerant distributor can be used to help distribute a two-phase refrigerant mixture to each of the evaporator units. In some HVAC systems, the two-phase refrigerant mixture can be distributed via, for example, a multiple-step distribution using Tee joints and/or three-way distributors. The multiple-step distribution can result in uneven refrigerant flows, pressure drops and/or uneven refrigerant distributions. These can undermine the performance of the evaporator units. Improvements can be made to improve refrigerant distribution, particularly two-phase refrigerant distribution, to an evaporator iinit(s).

Embodiments disclosed herein generally relate to methods, systems and apparatuses to help evenly distribute a two-phase refrigerant mixture info a plurality of evaporator units.

Embodiments disclosed herein are generally configured to direct the refrigerant (e.g. a two-phase refrigerant mixture) into a swirl/vortex motion in a cylinder-shaped distribution vessel of a refrigerant distributor. Because of, for example, a centrifugal force, the two-phase refrigerant mixture may form a relatively uniform region of mainly liquid refrigerant droplets along an internal surface of the cylinder-shaped distribution vessel. In some embodiments, the relatively uniform region of the liquid refrigerant, droplets can be distributed into evaporator units through a plurality of distribution lines that are in fluid communication with the distribution vessel, resulting in relatively uniform refrigerant distribution.

In some embodiments, the two-phase refrigerant mixture can be directed into a middle region of the distribution vessel through an inlet line. A splitter positioned at an end of the inlet line can be configured to split the two-phase refrigerant mixture flow into a plurality of refrigerant streams. The plurality of refrigerant streams can be direc ted into the distribution vessel in such a way that the plurality of refrigerant streams can swirl/vortex inside the distribution vessel.

References are made to the accompanying drawings that form a part hereof, and in which is shown by way of illustration of the embodiments in which the embodiments may be practiced. It is to be understood that, the terms used herein are for the purpose of describing the figures and embodiments and should not be regarded as limiting the scope of the present application.

Fig. 1 illustrates a HVAC system 100 that includes a compressor 110 generally configured to compress refrigerant vapor, a condenser 120 generally configured to condense the compressed refrigerant vapor to liquid refrigerant, an expansion device 130 generally configured to expand the liquid refrigerant to a two-phase refrigerant vapor/liquid mixture, and a plurality of evaporator units 150 configured to help heat exchange between the two-phase refrigerant mixture and, for example, air flowing across external surfaces of the e aporator units 150.

To help distribute the two-phase refrigerant mixture to the plurality of evaporator units 150, the HVAC system 100 includes a refrigerant distributor 140 that is generally configured to receive the two-phase refrigerant mixture from the expansion device 130 and distribute the two- phase refrigerant mixture into the plurality of evaporator units 150.

Each of the plurality of evaporator units 150 can be configured similar to each other. For example, each of the plurality of evaporator units 150 may have a similar capacity. Distributing the two-phase refrigerant mixture evenly into the individual evaporator units 150 may help, for example, increase the efficiency of the HVAC system 100.

Figs. 2A to 2G illustrate different aspects of a refrigerant distributor 200. Fig. 2A illustrates a transparent perspective view of the refrigerant distributor 200, and Fig. 2B illustrates a transparent end view of the refrigerant, distributor 200. As shown in Figs. 2A and 2B, the refrigerant distributor 200 generally includes a distribution vessel 210 that has a length L2 defining a longitudinal direction of the distribution vessel 210. The distribution vessel 210 generally includes a cylinder-shaped vessel body 213 extending in the longitudinal direction. The vessel body 213 has a first longitudinal end 210a and a second longitudinal end 210b. The distribution vessel 210 defines an internal chamber 212.

An inlet line 220 is attached to the distribution vessel 210 at a middle portion of the vessel body 213 along the length L2, with the notion that the location of inlet line 220 can be at other positions on the vessel body 213. In some embodiments, a center line C2 of the inlet 220 can intersect with a center line C3 of the distribution vessel 210 (as illustrated in Fig. 2B). The inlet line 220 is generally in fluid communication with the internal chamber 212 and is generally configured to direct refrigerant, such as a two-phase refrigerant mixture, into the internal chamber 212. Positioning the inlet line 220 at the mi ddle portion of the vessel body 213 along the length L2 may allow the refrigerant directed by the inlet, line 220 to be distributed toward the first longitudinal end 210a and the second longitudinal end 210b relatively evenly inside the internal chamber 212.

A distribution head 222 of the inlet line 220 extends into the internal chamber 212. The distribution head 222 generally has openings 223, 224 to allow the refrigerant to flow out of the inlet line 220 into the internal chamber 212. The openings 223 and 224 are generally on a wall 221 of the inlet line 220. The illustrated embodiment herein has two openings 223 and 224, with the notion that this is merely exemplary. In some other embodiments, the number of the openings on the wall 221 can be more than or less than two. The two openings 223 and 224 are generally configured to direct refrigerant tow ^r ard the first longitudinal end 210a and the second longitudinal end 210b respectively inside the internal chamber 212.

The distribution vessel 210 includes a plurality of distribution outlets 21 1 , 21 1b, 21 1c and 21 1 d. The distribution outlets 21 1 a, 2 l ib, 21 1 c and 21 1 d are in fluid communication with the internal chamber 212. Each of the distribution outlets 211a, 21 1b, 21 1 c and 21 i d can be configured to direct, refrigerant out of the internal chamber 212 into an evaporator uni t (e.g. the evaporator units 150 in Fig. 1 ).

The distribution outlets 21 1 a, 21 l b, 21 lc and 21 I d are generally positioned on the vessel body 213, and are generally positioned relatively close to the first, longitudinal end 210a or the second longitudinal end 210b along the length L2. In the illustrated embodiment, the distribution outlets 21 1 a and 21 lb are positioned close to the first longitudinal end 210a along the length L2, and the distribution outlets 21 l c and 21 I d are positioned close to the second longitudinal end 210b along the length L2. To help distribute the refrigerant evenly into the distribution outlets 21 l a to 21 I d, in some embodiments, a distance from the distribution outlet 21 la or 21 lb to the first longitudinal end 210a may be configured to be about the same as a distance from the distribution outlet 21 lc or 21 Id to the second longitudinal end 21 1 b along the length L2. Further, each of the distribution outlets 21 1 a to 21 Id may have a similar distance to the inlet line 220 along the length 12,

As illustrated in Fig, 2A, in some embodiments, the distribution vessel 210 can be positioned in a horizontal orientation, e.g. along the length L2, and the inlet line 220 can be positioned in a vertical orientation relati ve to the horizontal orientation of the distribution vessel 210. In this orientation, a total height of the distributor 200 in the vertical orientation can be relatively short, which may help install the distributor 200 in, for example, a vehicle air conditioning system, or other system that may have a height limitation. The refrigerant directed into the inlet line 220 can move downwardly in the vertical orientation, which can help reduce a pressure drop.

From the end view in Fig. 2B, the distribution outlets 21 1 c and 21 Id can be aligned along a common centerline CI that is about perpendicular to the centerline C2 of the inlet line 220. The distribution outlets 211c and 21 Id, therefore, can generally direct refrigerant out of the internal chamber 212 to opposite directions. It is noted that the distribution outlets 21 1a and 211b (not shown in Fig. 2B) may be also configured similarly relative to the centerline C2 of the mlet line 220.

As illustrated in Fig. 2B, the distribution vessel 210 has a center line C3. (See Fig. 3A.)

It is to be noted that in some embodiments, the distribution outlets can be positioned on the first end 210a and/or the second end 210b of the distribution vessel 213.

Referring to Figs. 2C to 2G, detai ls of the inlet line 220 are further illustrated. The inlet line 220 generally includes the wall 221 and a splitter 230 positioned into the wall 221 from an end 220a of the wal l 221. The wall 221 has openings 223 and 224 that are rel atively close to the end 220a of the wall 221, with the notion that the wall 221 can be configured to include other numbers of openings. The two openings 223 and 224 are generally configured to be opposite to each other relative to the centerline C2. The end 220a of the wall 221 and the two openings 223 and 224 are generally configured to be positioned in the internal chamber 212.

As illustrated in Fig. 2E, one embodiment of the splitter 230 is illustrated. The splitter 230 is generally configured to split a refrigerant flow 240 into two separate refrigerant streams 240a and 240b. The splitter 230 includes a split head 231 that, is generally configured to split the refrigerant flow 240 into two separate streams 240a and 240b. The splitter 230 also includes a first transition surface 232a and a second transition surface 232b that are generally configured to direct the refrigerant streams 240a and 240b respectively. In the side view as shown in Fig. 2E, the first transition surface 232a and the second transition surface 232b generally have smooth contours that direct the refrigerant stream 240 from a generally vertical direction toward a generally horizontal direction in the orientation as shown in Fig. 2E.

The two transition surfaces 232a and 232b generally converge toward the split head 231. As shown in Figs. 2D and 2E, the two transition surface 232a and 232b of the splitter 230 generally converge and form a relatively sharp and flat split head 231. The shape of the split head 231 may be generally configured to help reduce a pressure drop when splitting the refrigerant flow 240.

The splitter 230 is positioned internal to the wall 221 from the end 220a. When the splitter 230 is positioned inside the wail 221 , the splitter 230 is configured to generally seal the end 220a so as to prevent refrigerant from flowing out of the end 220a. As a result, the refrigerant can be directed out of the openings 223 and 224.

As illustrated in Figs. 2F and 2G, the transition surfaces 232a and 232b have edge lines 235a and 235b respectively. As illustrated, a portion of the edge line 235a of the transition surface 232a in Figs. 2F and 2G, in particular the portion of the edge line 235a corresponding to where the refrigerant, stream 240a (the shaded portion in Fig, 2F) leaves the transition surface 2.32a, can be shaped to align with a portion of a perimeter of the opening 223, (See Fig, 2G.) When the refrigerant stream 240a leaves the transition surface 232a, the alignment between the transition surface 232a and the opening 223 can help reduce the pressure drop caused by directing the refrigerant stream 240a out of the opening 223. The opening 224 and the transition surface 232b can also be similarly configured.

It is to be appreciated that the embodiment as disclosed herein is exemplary. The splitter can be configured differently. Generally, the splitter is configured to split a refrigerant flow into a plurality of separate refrigerant streams in different directions, and direct the separate refrigerant streams toward different openings. In some embodiments, the splitter can be configured to have more than two transition surfaces converging toward a splitter head. Each of the transition surfaces can be configured to direct a refrigerant stream toward a direction that is different from other refrigerant streams. Each refrigerant flow can be directed toward an opening on the wall of the inlet line.

Referring to Figs. 3 A and 3B, the operation of the distributor 200 is further il lustrated. The arrows generally illustrate the direction of the refrigerant in the distribution vessel 210. When the inlet line 220 is installed on the distribution vessel 210, the distribution head 222 is positioned inside the internal chamber 212. The cylinder-shaped vessel body 213 has the centeriine C3. The centeriine C3 generally defines a longitudinal direction.

Referring to Fig. 3C, the openings 223 and 224 of the distribution head 222 are positioned angularly relative to the centeriine C3. That is when the refrigerant stream 240a or 240b is directed out of the opening 223 or 224 respectively, the initial direction of the refrigerant stream is generally not aligned with the centeriine C3 and generally forms an angle with the centeriine C3. As illustrated in Fig. 3C, the initial direction of the refrigerant streams 240a or 240b forms an angle a ₃ or a ₃ ' respectively that is not 90 or 180 degrees relative to the centeriine C3 of the vessel body 213. The refrigerant streams 240a or 240b can then be forced to turn by the internal surface of the vessel body 213. Consequently, the refrigerant streams 240a and 240b can form a swirl/vortex motion in the internal chamber 212.

The term "angular" generally means a direction that forms an angle with, for example, the centeriine C3 that is neither 0° nor 180° (i.e. the direction is not aligned with the centeriine C3). When the refrigerant stream 240a or 240b is directed in a direction that is angular to the centeriine (13, the refrigerant stream 240a or 240b can interact with an internal surface of the distribution vessel 210 and form a swirl/ ortex motion.

Fig. 3B illustrates a schematic diagram showing the effect of the swirl/ ortex motion of the refrigerant streams 240a and 240b when the refrigerant flow 240 is a two-phase refrigerant mixture including a liquid refrigerant portion and a refrigerant vapor portion.

In the internal chamber 212, in a proximate region 310 that is relatively close to where the distribution head 222 is, the swirl/vortex of the refrigerant streams 240a and 240b can generally mobil ize the liquid refrigerant portion and the refrigerant vapor portion of the two- phase refrigerant mixture. The liquid refrigerant portion is generally formed by refrigerant liquid droplets. Because of the swirling, the refrigerant liquid droplets can generally suspend in the interna! chamber 212. In distal regions 320 that are further away from the distribution head 222 compared to the proximal region 310, at least due to centrifugal forces, the liquid refrigerant droplets can be pushed away from the centerline C3. In the distal regions 320, a relatively uniform region of mainly liquid refrigerant droplets can be formed against the internal surface of the vessel body 213. Compared to the liquid refrigerant portion, the refrigerant vapor portion generally stays relatively closer to the centerline€3 compared to the liquid refrigerant droplets and therefore form a refrigerant vapor zone 330 that mainly includes the refrigerant vapor portion.

The distribution outlets 21 la to 21 Id can be generally positioned on the vessel body 213 corresponding to where the relatively uniform region of mainly liquid refrigerant droplets (i.e. the distal region 320) is. Generally, the relatively uniform region of mainly liquid refrigerant droplets can help the refrigerant being distributed into the distribution outlets 211a to 211 d relatively evenly.

In the illustrated embodiments, the distance of the distribution outlets 21 1a to 21 id relative to the inlet line 220 may be similar to each other. This may help ensure an amount of refrigerant that flows into the distribution outlets 21 la to 21 Id to be relatively similar. It is noted, however, that the distribution outlets 21 la to 21 1 d can be positioned at other locations on the vessel body 233 in the longitudinal direction. In some embodiments, the number of the distribution outlets can be more than or less than four.

The refrigerant can be directed by the distribution outlets 21 1a to 23 3d to a plurality of evaporators (i.e. the evaporators 150 in Fig. 1) of a HVAC system (i.e. the HVAC system 100 in Fig. 1). Evenly distributing the refrigerant into the evaporators may help increase the efficiency of the HVAC system.

It is to be appreciated that the general principle of distributing refrigerant in a distribution chamber is to direct a refrigerant flow into the distribution chamber in a direction that is angular to a longitudinal direction of the distribution chamber. Because of the direction of the refrigerant flow is angular to the longitudinal direction, the refrigerant flow can interact with the internal surface of the distribution chamber and produce a swirl in g/vortexmg refrigerant flow in the distribution chamber. The centrifugal force produced by the swirimg/vortexmg can help form a zone of mainly refrigerant liquid along the internal surface of the distribution chamber. It is noted that in some embodiments, the refrigerant can be directed at one end of the distribution chamber rather than in the middle portion of the distribution chamber. In some embodiments, the refrigerant flow can be directed into the distribution chamber as one flow instead of two separated flow, and a splitter may not be necessary.

It is noted that even though the embodiments as disclosed herein are directed to distributing refrigerant in a HVAC system, the principles as disclosed herein can be applied to distributing other types of fluids. Generally, the principles as disclosed herein may be applied to distributing a liquid/vapor fluid mixture in any suitable systems.

Any aspects 1 -5 can be combined with any aspects 6-17. Any aspects 6-12 can be combined with any aspects 13-17.

Aspect 1. A refrigerant distributor, comprising;

a distribution vessel having a cylinder-shaped profile and a longitudinal direction;

a plurality of distribution outlets, the plurality of distribution outlets in fluid

communication with an internal chamber of the distribution vessel; and

a refrigerant inlet, line configured to direct, refrigerant into the internal chamber of the distribution vessel,

wherem the refrigerant inlet line has an opening positioned inside the internal chamber, the first opening is on a wail of the inlet line, and the opening opens to a direction that is angular to the longitudinal direction.

Aspect 2. The refrigerant distributor of aspect 1 , further comprising:

a second opening positioned inside the internal chamber, wherein the second opening is on the wall of the inlet line. Aspect 3. The refrigerant distributor of aspects 1-2, wherein the inlet line has a refrigerant flow splitter configured to direct the refrigerant flow into both of the opening and the second opening. Aspect 4. The refrigerant distributor of Aspects 1 -3, wherein the distributor outlets are positioned on a body of the distribution vessel,

Aspect 5. The refrigerant distributor of aspects 1-4, wherein the refrigerant inlet line is positioned in a middle region of the distribution vessel in the longitudinal direction.

Aspect 6. A HVAC system comprising:

a refrigerant distributor; and

a plurality of evaporator units;

wherein the refrigerant distributor includes,

a distribution vessel having a cylinder-shaped profile and a longitudinal direction;

a plurality of distribution outlets, the plurality of distribution outlets in fluid

communication with an internal chamber of the distribution vessel:

each of the plurality of evaporator units connected to one of the plurality of distribution outlet, and

a refrigerant inlet line configured to direct refrigerant into the internal chamber of the distribution vessel, the refrigerant inlet line having an opening positioned inside the internal chamber and on a wall of the inlet line, the opening opens to a direction that, is angular to the longitudinal direction.

Aspect, 7. The HVAC system of aspect 6, further comprising:

a second opening positioned inside the interna] chamber, wherein the second opening is on the wall of the inlet line.

Aspect 8. The HVAC system of aspects 6-7, wherein the refrigerant inlet line is positioned in a middle region of the distribution vessel.

Aspect 9. The HVAC system of aspects 7-8, wherein the inlet line has a refrigerant flow splitter configured to direct the refrigerant flow into both of the opening and the second opening.

Aspect 10. The H VAC system of aspects 6-9, wherein the distributor outlets are positioned on a body of the distribution vessel. Aspect 1 1 . The HVAC system of aspects 6-10, wherein the distributor vessel is positioned in a horizontal orientation.

Aspect, 12. The HVAC system of aspects 6-1 1 , wherein a centerline of the refrigerant inlet line intersects with a centerline of the distributor vessel.

Aspect 13. A method of distributing refrigerant, comprising:

directing a refrigerant flow into a cylinder-shaped internal chamber of a refrigerant distributor; and

creating a swirl motion in the refrigerant flow along a longitudinal direction of the internal chamber.

Aspect 14. The method of aspect 13 , wherein creating a swirl motion in the refrigerant flow along a longitudinal direction of the distributor chamber includes directing the refrigerant stream in a direction that is angular relative to the longitudinal direction.

Aspect 15. The method of aspects 13-14, further comprising:

directing refrigerant from the swirling refrigerant flow in the internal chamber into one or more evaporator units.

Aspect 16. The method of aspects 13-15, further comprising splitting the refrigerant flow into a plurality of separate refrigerant streams.

Aspect, 17. The method of aspects 16, wherein creating a swirl motion in the refrigerant flow along a longitudinal direction of the interna] chamber includes creating a swirl motion in the plurality of separate refrigerant streams along a longitudinal direction of the internal chamber.

With regard to the foregoing description, it is to be understood that changes may be made in detail, without departing from the scope of the present invention. It is intended that the specification and depicted embodiments are to be considered exemplary only, with a true scope and spirit of the invention being indicated by the broad meaning of the claims.