WO2014205799A1

WO2014205799A1 - Microchannel heat exchangers

Info

Publication number: WO2014205799A1
Application number: PCT/CN2013/078412
Authority: WO
Inventors: Xiaojun Wu; Jing Wang; Guohui Zhong; Yugao GUO; Guanghzi DENG
Original assignee: Ingersoll Rand (China) Industrial Technologies; Thermo King Corporation
Priority date: 2013-06-28
Filing date: 2013-06-28
Publication date: 2014-12-31

Abstract

A modular microchannel heat exchanger that can be, for example, used with a BUS HVAC system is provided. The BUS HVAC system can be configured to include a plurality of the microchannel heat exchanger module to meet, for example, a capacity requirement. The microchannel heat exchanger module may also include features that may help evenly distribute refrigerant in the microchannel heat exchanger module. A splitter with apertures may be included to help distribute the refrigerant in a longitudinal direction. One or more vertical structures may be included to slow down a velocity of the refrigerant.

Description

MICROCHANNEL HEAT EXCHANGERS

Field

The disclosure herein relates to a microchannel heat exchanger that may be used in a heating, ventilation, and air-conditioning ("HVAC") system, such as an evaporator of a bus HVAC system. Generally, methods, systems, and apparatuses are described that are directed to a modular microchannel heat exchanger that may include features to help distribute refrigerant evenly in the microchannel heat exchanger.

Background

Generally, a microchannel heat exchanger may include a plurality of flat microchannel pipes arranged in parallel. The microchannel heat exchangers can help heat exchange between a first fluid flow through the flat microchannel pipes internally and a second fluid flowing across outer surfaces of the flat microchannel pipes. Microchannel heat exchangers may be relatively compact and have relatively high heat transfer efficiency. Microchannel heat exchangers can be used in HVAC system for various applications.

Summary

Microchannel heat exchangers can be used in a HVAC system as, for example, an evaporator and/or a condenser. However, it is relatively difficult to distribute a two-phase refrigerant (a liquid/vapor refrigerant mixture) in the microchannel heat exchanger. Therefore, the microchannel heat exchanger is rarely used as an evaporator in a HVAC system.

A modular microchannel heat exchanger is provided for applications such as a bus HVAC system. Improvements to the microchannel heat exchanger that can help evenly distribute refrigerant to microchannel pipes of the microchannel heat exchanger are also provided.

In some embodiments, the bus HVAC system can be configured to include one or more microchannel heat exchanger modules to meet, for example, a capacity requirement of the bus HVAC system.

In some embodiments, each of the microchannel heat exchangers of the bus HVAC system may include an inlet configured to direct refrigerant into the microchannel heat exchanger and an outlet configured to direct refrigerant out of the microchannel heat exchanger. The bus HVAC system may include an inlet pipe configured to receive refrigerant, which can form fluid communication with the inlets of the microchannel heat exchangers and direct the refrigerant to the inlets of the microchannel heat exchangers. In some embodiments, the bus HVAC system may include an outlet pipe forming fluid communication with the outlets of the microchannel heat exchangers and receive refrigerant flowing out of the outlets of the microchannel heat exchangers.

In some embodiments, the inlet pipe may be configured to receive two-phase refrigerant. The microchannel heat exchangers can function as an evaporator of the bus HVAC system.

In some embodiments, each of the microchannel heat exchangers may be configured to have a first bank and a second bank. The inlet may be configured to deliver refrigerant into the first bank, and the outlet may be configured to receive refrigerant from the second bank. The first bank and the second bank may be overlapped with each other so that a fan can be configured to blow air across the surfaces of both of the first and second banks.

In some embodiments, each of the microchannel heat exchangers has a top portion and a bottom portion. The inlet can be configured to direct the refrigerant toward the top portion of the first bank of the microchannel heat exchanger and the outlet can be configured to direct the refrigerant out of the second bank of the microchannel heat exchanger. The first bank and the second bank can form fluid communication through the bottom portion of the microchannel heat exchanger.

The microchannel heat exchanger can also be configured to include features that may help evenly distribute refrigerant to the microchannel pipes. In some embodiments, the microchannel heat exchanger may include a splitter that includes a flat plate with a plurality of apertures. The splitter can be configured to cover end openings of microchannel pipes that are configured to receive refrigerant directed from the inlet. In some embodiments, each of the apertures may be positioned between two neighboring microchannel pipes.

In some embodiments, the splitter may include a vertical structure rising from the flat plate in a direction that is perpendicular to a flow direction of the refrigerant directed into the microchannel heat exchanger by the inlet. In some embodiments, the vertical structure may include a blocking portion and a flow through portion. The blocking portion may be configured to block the refrigerant, and the flow through portion may be configured to allow refrigerant to flow through.

In some embodiments, the splitter may include a second vertical structure rising from the flat plate in a direction that is perpendicular to the flow direction of the refrigerant. The second vertical structure may be positioned further away from the inlet than the first vertical structure in a longitudinal direction. The second vertical structure may include a blocking portion and a flow through portion, and the flow through portion of the second vertical structure may be smaller than the flow through portion of the first vertical structure.

In some embodiments, when the microchannel heat exchanger has a first bank and a second bank, the inlet may be configured to direct refrigerant toward the first bank at the top portion of the microchannel heat exchanger, and the outlet may be configured to direct refrigerant out of the second bank at the top portion of the microchannel heat exchanger.

In some embodiments, the first bank and a second bank may form fluid communication at the bottom portion of the microchannel heat exchanger. In some embodiments, the

microchannel heat exchanger may include a second splitter that includes a flat plate configured to cover end openings of the microchannel pipes of the second bank at the bottom portion of the microchannel heat exchanger.

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.

Figs. 1 A to 1C illustrate an embodiment of a bus HVAC system that includes a plurality of microchannel heat exchanger modules. Fig. 1 A illustrates the bus HVAC system with a cover of the bus HVAC system removed to illustrate the interior of the bus HVAC system. Fig. IB illustrates a perspective view of one microchannel heat exchanger module. Fig. 1C illustrates two microchannel heat exchanger modules of the bus HVAC system that are arranged in parallel.

Figs. 2A to 2C illustrate an embodiment of a microchannel heat exchanger. Fig. 2A illustrates an exploded view of the microchannel heat exchanger. Fig. 2B illustrates an end sectional view of the microchannel heat exchanger. Fig. 2C illustrates a splitter that is positioned in the microchannel heat exchanger.

Detailed Description

A microchannel heat exchanger can be generally used in a HVAC system for various applications. However, it is relatively difficult to distribute a two-phase refrigerant (a liquid/vapor refrigerant mixture) in the microchannel heat exchanger. Therefore, the

microchannel heat exchanger is rarely used as an evaporator in a HVAC system.

Embodiments as described herein generally relate to a microchannel heat exchanger module that can be used, for example, as an evaporator. In some embodiments, the

microchannel heat exchanger module can be used as an evaporator of a bus HVAC system. The microchannel heat exchanger module may be relatively compact and can be modularized to meet a capacity requirement of the bus HVAC system, and may be suitable generally for transport HVAC systems, such as a bus HVAC system, because they are relatively compact and have good heat exchange efficiency.

The microchannel heat exchanger module may also include features that may help evenly distribute refrigerant in the microchannel heat exchanger module. In some embodiments, a flat splitter with apertures may be included to help distribute the refrigerant in a longitudinal direction. In some embodiments, one or more vertical structures rising from the flat splitter may be included to help distribute the refrigerant.

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.

Figs. 1 A to 1C illustrate a bus HVAC system 100 that includes a plurality of

microchannel heat exchanger modules 1 10 that are configured to work as an evaporator of the bus HVAC system 100. A cover of the bus HVAC system 100 has been removed to illustrate the interior of the bus HVAC system. The bus HVAC system 100 also includes a plurality of fans 120 configured to drive air to flow across external surfaces of the microchannel heat exchanger modules 1 10 so that the air can exchange heat with and be conditioned by refrigerant flowing inside the microchannel heat exchanger modules 110. As illustrated in Fig. 1 A, in some embodiments, each of the microchannel heat exchanger modules 1 10 can be configured to be positioned near one of the fans 120. In some embodiments, as illustrated in Fig. 1 A, the plurality of microchannel heat exchanger modules 110 can be arranged along two sides 101 and 102 of the bus HVAC system 100.

The bus HVAC system 100 can be placed, for example, on a rooftop of a bus.

Dimensions of the bus HVAC system 100 may be limited because of space limitations on the rooftop of the bus. For example, a height HI of the bus HVAC system 100 may be limited due to design specifications. On the other hand, the bus HVAC system 100 may also have to meet a capacity requirement so that the bus HVAC system can have a capacity that is enough to, for example, cool down a passenger compartment of the bus to a predetermined temperature.

As illustrated in Figs. 1 A to 1C, the bus HVAC system 100 may include one or more microchannel heat exchanger modules 1 10. Each of the microchannel heat exchanger modules 1 10 can be configured to have a similar heat exchange capacity, with the appreciation that the heat exchange capacity of the microchannel heat exchanger modules 1 10 can be different. A plurality of the microchannel heat exchanger modules 1 10 can be used to meet the capacity requirement of the bus HVAC system 100. By using the microchannel heat exchanger modules 1 10, different capacity requirements of the bus HVAC system 100 can be met relatively easily by choosing different number of the microchannel heat exchanger modules 110.

As illustrated in Fig. IB, the microchannel heat exchanger module 110 has a height H2 that can be configured so that the microchannel heat exchanger module 1 10 can be fitted in the bus HVAC system 100.

The microchannel heat exchanger module 110 can be configured to include a first bank 1 10a and a second bank 110b. The first bank 1 10a and the second bank 110b generally include a plurality of microchannel pipes 1 11. The first bank 1 10a and the second bank 1 10b are generally configured to overlap with each other so that air can be generally directed across the first and second banks 110a and 110b sequentially. (See for example the block arrows in Fig. IB.) It is noted that in some embodiments, the microchannel heat exchanger module 110 can include more than two banks or can be just one bank. Including more than one bank in the microchannel heat exchanger module 110 can help increase the heat exchange capacity of the microchannel heat exchanger module 110.

The microchannel heat exchanger module 110 includes an inlet 112 that is configured to allow refrigerant to flow into the microchannel heat exchanger module 110 and an outlet 114 that is configured to allow refrigerant to flow out of the microchannel heat exchanger module 1 10. The refrigerant can be distributed into the plurality of the microchannel pipes 111 of the microchannel heat exchanger module 110. When air is directed across external surfaces of the microchannel pipes 111 of the microchannel heat exchanger module 110, the air can exchange heat with the refrigerant and be conditioned by the refrigerant. Typically, as illustrated in Fig. 1 A, when the microchannel heat exchanger modules 1 10 are used as an evaporator of the bus HVAC system 100, two-phase refrigerant with a relatively low temperature than an outside temperature of a bus can be directed into the microchannel heat exchanger modules 1 10 to condition the air inside a bus (not shown).

As illustrated in Fig. 1C, the plurality of microchannel heat exchanger modules 110 can be arranged in parallel. Each of the microchannel heat exchanger modules 110 has the inlet 112 and the outlet 1 14. The inlets 1 12 of the plurality of the microchannel heat exchanger modules 110 can form fluid communication with a common inlet pipe 113. The outlets 114 of the plurality of the microchannel heat exchanger modules 110 can form fluid communication with a common outlet pipe 1 15.

In operation, refrigerant (e.g. two-phase refrigerant) can be distributed into the inlet pipe 1 13. The refrigerant can be further distributed into the inlet 112 of each microchannel heat exchanger module 110. After heat exchange in the microchannel heat exchanger modules 1 10 occurs, the refrigerant can be directed out of the outlet 114 of the microchannel heat exchanger modules 110, and then can be directed into the outlet pipe 115. Depending on the design specification (e.g. the capacity requirement of the bus HVAC system 100), the inlet pipe 1 13 and the outlet pipe 115 can be configured to connect to one or a plurality of the microchannel heat exchanger modules 110.

To help evenly distribute the refrigerant into and/or direct the refrigerant out of the plurality of microchannel heat exchanger modules 1 10, generally a specific distance between the inlets 112 and/or the outlets 114 to the inlet pipe 113 and/or the outlet pipe 115 respectively is provided for each microchannel heat exchanger module 1 10. As illustrated in Fig. 1C, for example, the outlet 114 of each microchannel heat exchanger module 1 10 generally has a "L" shape, which includes a first stem 114a and a second stem 1 14b. The first stem 114a generally extends in a vertical direction (see for example the vertical direction V as illustrated in Fig. 2A) and has a distance D3 (which is generally the length of the second stem 1 14b) from the outlet pipe 115 (e.g. the length of the second stem 114b). Each of the microchannel heat exchanger modules 110 has a similar distance D3 between the outlet 1 14 and the outlet pipe 115, which may help evenly direct the refrigerant out of the microchannel heat exchanger modules 110. The inlet 112 of each microchannel heat exchanger modules 110 can also be configured to have a similar distance relative to the inlet pipe 113 to help evenly distribute refrigerant into the microchannel heat exchanger modules 1 10.

It is to be appreciated that in some embodiments, the microchannel heat exchanger modules in the bus HVAC systems may be different from each other. In some embodiments, the capacity of each microchannel heat exchanger module, the number of microchannel pipes of each microchannel heat exchanger module, and/or a total number of the microchannel heat exchanger modules may be determined based on, for example, the capacity requirement of the bus HVAC system, the airflow velocity/volume in the region where the microchannel heat exchanger module is to be installed; the velocity of the refrigerant in the inlet pipe, and space limitations. In some embodiments, a distance between two neighboring microchannel heat exchanger modules the bus HVAC system can be about the same. In some embodiments, the distance between two neighboring microchannel heat exchanger modules can be different.

Figs. 2A to 2C illustrate an embodiment of a microchannel heat exchanger 210 that can be used as the microchannel heat exchanger module 1 10 in the bus HVAC system 100. It is to be appreciated that the microchannel heat exchanger 210 can also be applied to other applications. The features of the microchannel heat exchanger 210 as described herein generally can help evenly distribute refrigerant in the microchannel heat exchanger 210. These features can also be used with other suitable microchannel heat exchangers, such as a microchannel heat exchanger with one bank.

The microchannel heat exchanger 210 is generally configured to work in the vertical orientation V as shown in Fig. 2 A. The microchannel heat exchanger 210 is configured to have a first bank 210a and a second bank 210b. The first bank 201a and the second bank 210b are configured to include a plurality of microchannel pipes 21 1.

An inlet 212 is configured to direct refrigerant toward a top portion 213 of the microchannel heat exchanger 210. The microchannel pipes 211 have end openings 219 in the top portion 213.

The top portion 213 is covered by a top cover 221. The top portion 213a is configured to have first and second roof-like structures 221a and 221b. When the top cover 221 is positioned on top of the top portion 213 of the microchannel heat exchanger 210, the first roof-like structure 221a is generally aligned with and covers the first bank 210a. The second roof-like structure 221b is generally aligned with and covers the second bank 210b. When the top cover 221 is installed to cover the top portion 213 of the microchannel heat exchanger 210, the top cover 221 can generally provide a seal between the first bank 210a and the second bank 210b, as illustrated in Fig. 2B. The inlet 212 is generally configured to direct refrigerant into the first bank 210a through the end openings 219. An outlet 214 is generally configured to direct refrigerant out of the second bank 210b.

A bottom portion 215 of the microchannel heat exchanger 210, including the first bank 210a and the second bank 210b, is generally covered by a bottom cover 223. The bottom cover 223 is generally configured to allow fluid communication between the first bank 210a and the second bank 210b through end openings (not shown) in the bottom portion 215, as illustrated in Fig. 2B.

The microchannel heat exchanger 210 is configured to include features that can help evenly distribute refrigerant. Generally, these features can help distribute the refrigerant along the longitudinal direction L of the microchannel heat exchanger 210. Referring to Figs. 2A and 2B, the first bank 210a and the second bank 210b are configured to include a first and second splitters 230a and 230b respectively to help evenly distribute refrigerant to microchannel pipes 211. The splitters 230a and 230b generally include a flat plate 232a and 232b respectively extending along the longitudinal direction L with one or more apertures 231 through the fiat plate 232a and 232b.

Generally, the splitter 230a and/or 230b are positioned to cover the end openings 219 of the microchannel pipes 21 1 that are configured to allow refrigerant to flow into the microchannel pipes 21 1. The inlet 212 is configured to direct refrigerant to the top portion 213 of the first bank 210a. The first splitter 230a is positioned at the top portion 213 of the first bank 210a to cover the end openings 219 of the first bank 210a so that when the refrigerant is directed toward the first bank 210a through the inlet 212, the refrigerant can be distributed by the first splitter 230a into the microchannel pipes 211.

After refrigerant flows through the microchannel pipes 211 of the first bank, the refrigerant can be directed into the second bank 210b through the bottom portion 215 of the second bank 210b. The second splitter 230b is positioned to cover the end openings 219 at the bottom portion 215 of the second bank 210b so that when the refrigerant is directed toward the second bank 210b through the bottom cover 223, the refrigerant can be distributed by the second splitter 230b into the microchannel pipes 21 1.

The flat plates 230a and 230b can help distribute the refrigerant along the longitudinal direction L. The apertures 231 can allow the refrigerant to flow into the microchannel pipes 211 through the apertures 231. Therefore, the first splitter 230a and the second splitter 230b can help distribute the refrigerant in the longitudinal direction L while allowing the refrigerant to be distributed into the microchannel pipes 21 1 through the apertures 231. As illustrated in Figs 2A and 2C, the apertures 231 can be slots that extend in a direction that is generally perpendicular to the longitudinal direction L on the splitters 230a and/or 230b. It is to be appreciated that the size of the apertures 231 and/or the arrangement/distribution of the apertures 231 along the longitudinal direction L can be varied. In some embodiments, the splitter 230a and/or 230b can be configured to have evenly arranged apertures 231 along the longitudinal direction L. In some embodiments, a total number of the apertures 231 may be about ½ to ¼ of a total number of the microchannel pipes 211. In some embodiments, each aperture 231 may be positioned to overlap with two neighboring microchannel pipes 211. In some embodiments, the size of the aperture 231 may be about twice of a cross-section size of the microchannel pipe 211.

As illustrated in Figs. 2A, 2B and 2C, the first splitter 230a may have at least one vertical structure 241, 242, 243 that is generally configured to help distribute the refrigerant along the longitudinal direction L when the refrigerant is directed toward the first bank 210a by the inlet 212. The vertical structure 241, 242, 243 generally rises from the flat plate 232a of the first splitter 230a. When the refrigerant initially distributed into the first bank 210a by the inlet 212, the velocity of the refrigerant along the longitudinal direction L may be relatively high. As a result, the refrigerant may tend to concentrate toward a longitudinal end 235 that is on the opposite side of the inlet 212 relative to the first bank 210a. The vertical structure 241, 242, 243 can generally help distribute the refrigerant in directions that are away from the longitudinal direction L.

As illustrated in Fig. 2C, the vertical structures 241, 242 and 243 generally include a flow through portion (e.g. an opening) 241a, 242a and 243a respectively and a blocking portion (e.g. a solid portion) 241b, 242b, 243b respectively. As illustrated in Fig. 2C, the blocking portions 241b, 242b and 243b can be configured to surround the flow through portions 241b, 242b and 242b. The blocking portions 241a, 242a and 243a can generally help distribute the refrigerant in directions that are away from the longitudinal direction L, while the flow through structures 241b, 242b and 243b can allow the refrigerant to flow through in the longitudinal direction L. Generally, the blocking portions 241b, 242b and 243b and the flow through portions 241b, 242b and 243b are generally substantially perpendicular to the longitudinal direction L.

The vertical structures 241, 242 and 243 generally divide the first splitter into region LI, L2, L3 and L4 along the longitudinal direction L. When the refrigerant velocity along the longitudinal direction L is relatively high, the refrigerant flow tends to concentrate toward the regions L4 and/or L3. The vertical structures 241 , 242 and 243 can help retain the refrigerant in other regions, such as regions LI and L2. It is to be appreciated that the vertical structures 241, 242 and 243 as illustrated herein are exemplary. The configurations and/or number of the vertical structures can vary. Generally, the vertical structure can be a structure that is positioned in the refrigerant flow to disperse the refrigerant flow in directions that are away from the longitudinal direction L.

A total number of the vertical structures can be more or less than three. A length of the regions LI , L2, L3 and L4 along the longitudinal direction L can also be varied. In some embodiments, the length of the regions LI , L2, L3 and L4 is about 5:4:3:2.

A size of the flow through structures 241a, 242a and 242c can also be varied. Generally, the vertical structure 241, which is the furthest away from the inlet 212 in the longitudinal direction L, has the smallest flow through structure 241a. The vertical structure 243, which is the closest from the inlet 212 in the longitudinal direction L, has the largest flowing structure 243a. The flow through structure 242a of the vertical structure 242 that is positioned between the vertical structures 241 and 243 is configured to have a size that is between the flowing structure 241a and the flowing structure 243a. Generally, the further away from the inlet 212 is, the smaller the flowing structure. In some embodiments, the size of the flow through structures 241a, 242a and 243a respectively may have a ratio of about 1 :2:4.

It is to be appreciated that the total number of the vertical structures, the size of the flow through structures and/or the blocking structure, and/or the arrangement of the vertical structures along the longitudinal direction L can be varied based on, for example, the velocity of the refrigerant flow and/or capacity of the microchannel heat exchanger 210. The configuration of the vertical structures may also be optimized, for example, in a laboratory setting.

In operation, the refrigerant may be directed into the first bank 210a through the inlet 212. When the refrigerant is initially distributed into the first bank 210a, the velocity of the refrigerant may be relatively high, which may cause the refrigerant to concentrate toward the end 235 that is opposite to where the inlet 212 is. The vertical structures 241, 242 and 243 can help disperse the refrigerant away from the longitudinal direction L and therefore help evenly distribute the refrigerant along the longitudinal direction L. The refrigerant can be distributed into the microchannel pipes 211 by the first splitter 230a. The first splitter 230a can help distribute the refrigerant in the longitudinal direction L and the apertures 231 can allow the refrigerant into the microchannel pipes 211. The refrigerant can have heat exchange with, for example, air flowing across the external surfaces of the microchannel pipes 211 while the refrigerant flowing from the top portion 213 toward the bottom portion 215 of the microchannel pipes 21 1 of the first bank 210a. After flowing out of the microchannel pipes 211 of the first bank 210a, the refrigerant can be collected in the bottom cover 223 and flow toward the microchannel pipes 211 of the second bank 210b in the bottom cover 223. The refrigerant can be distributed into the microchannel pipes 211 of the second bank 210b through the second splitter 230b. The refrigerant can exchange heat with, for example, air flowing across the external surfaces of the microchannel pipes 21 1 of the second bank 210b. After flowing through the second bank 210b, the refrigerant can be directed out of the second bank 210b through the outlet 214.

It is noted that the embodiments as disclosed herein are exemplary. The embodiments as described herein can be used with other applications, such as working as condensers or used in other HVAC systems.

Any aspects 1-7 can be combined with any aspects 8-15.

Aspect 1. A bus HVAC system, comprising:

a plurality of microchannel heat exchangers;

each of the microchannel heat exchangers having an inlet configured to direct refrigerant into the microchannel heat exchanger and an outlet configured to direct refrigerant out of the microchannel heat exchanger;

an inlet pipe configured to receive refrigerant; and

an outlet pipe;

wherein the inlet of each of the microchannel heat exchangers is in fluid communication with the inlet pipe, the inlet pipe is configured to direct refrigerant into the inlet of the microchannel heat exchanger, the outlet of each of the microchannel heat exchangers is in fluid communication with the outlet pipe, and the outlet pipe is configured to receive refrigerant flowing out of the outlets of the microchannel heat exchangers.

Aspect 2. The bus HVAC system of aspect 1, wherein the inlet pipe is configured to receive two-phase refrigerant.

Aspect 3. The bus HVAC system of aspects 1-2, wherein each of the microchannel heat exchangers is configured to have a first bank and a second bank, the inlet is configured to deliver refrigerant into the first bank, and the outlet is configured to receive refrigerant from the second bank.

Aspect 4. The bus HVAC system of aspects 1-3, wherein each of the microchannel heat exchangers has a top portion and a bottom portion, the inlet is configured to direct the refrigerant toward the top portion of the first bank of the microchannel heat exchanger and the outlet is configured to direct the refrigerant out of the second bank of the microchannel heat exchanger, and the first bank and the second bank forms fluid communication through the bottom portion of the microchannel heat exchanger.

Aspect 5. The bus HVAC system of aspects 1-5, wherein the microchannel heat exchanger includes a splitter configured to distribute refrigerant directed into the microchannel heat exchanger by the inlet, the splitter includes a flat plate with a plurality of apertures, and the splitter is configured to cover end openings of microchannel pipes of the microchannel heat exchanger.

Aspect 6. The bus HVAC system of aspect 5, wherein the splitter include a vertical structure extending from the flat plate in a direction that is substantially perpendicular to a flow direction of the refrigerant directed into the microchannel heat exchanger by the inlet.

Aspect 7. The bus HVAC system of aspect 6, wherein the vertical structure include a blocking portion and a flow through portion, the blocking portion is configured to block the refrigerant, and the flow through portion is configured to allow refrigerant to flow therethrough.

Aspect 8. A microchannel heat exchanger, comprising:

a plurality of microchannel pipes, the plurality of microchannel pipes having a top portion and a bottom portion;

an inlet configured to direct refrigerant toward the top portion of the microchannel pipes; a splitter including a flat plate, the flat plate configured to cover ends of the plurality of microchannel pipes on the top portion, wherein the fiat plate of the splitter includes a plurality of apertures configured to allow refrigerant to flow therethrough.

Aspect 9. The microchannel heat exchanger of aspect 8, wherein each of the apertures is positioned between two neighboring microchannel pipes.

Aspect 10. The microchannel heat exchanger of aspects 8-9, wherein the splitter includes a first vertical structure rising from the flat plate in a direction that is perpendicular to a flow direction of the refrigerant, the splitter includes a blocking portion and a flow through portion.

Aspect 11. The microchannel heat exchanger of aspects 8-10, wherein the splitter includes a second vertical structure rising from the flat plate in a direction that is substantially perpendicular to a flow direction of the refrigerant, the second vertical structure is further away from the inlet than the first vertical structure in a longitudinal direction.

Aspect 12. The microchannel heat exchanger of aspect 1 1, wherein the second vertical structure includes a blocking portion and a flow through portion, the flow through portion of the second vertical structure is smaller in size than the flow through portion of the first vertical structure. Aspect 13. The microchannel heat exchanger of aspects 8-12, comprising:

a first bank and a second bank, each of which includes a portion of the plurality of microchannel pipes,

wherein the inlet is configured to direct refrigerant toward the first bank at the top portion of the microchannel heat exchanger, and the outlet is configured to direct refrigerant out of the second bank at the top portion of the microchannel heat exchanger.

Aspect 14. The microchannel heat exchanger of aspect 13, wherein the first bank and a second bank form fluid communication at the bottom portion of the microchannel heat exchanger.

Aspect 15. The microchannel heat exchanger of aspect 13-14, comprising:

a second splitter, wherein the second splitter includes a flat plate configured to cover ends of the microchannel pipes of the second bank at the bottom portion of the microchannel heat exchanger, wherein the flat plate of the splitter includes a plurality of apertures configured to allow refrigerant to flow therethrough.

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.

Claims

1. A bus HVAC system, comprising:

a plurality of microchannel heat exchangers;

an inlet pipe configured to receive refrigerant; and

an outlet pipe;

2. The bus HVAC system of claim 1, wherein the inlet pipe is configured to receive two-phase refrigerant.

3. The bus HVAC system of claim 1, wherein each of the microchannel heat exchangers is configured to have a first bank and a second bank, the inlet is configured to deliver refrigerant into the first bank, and the outlet is configured to receive refrigerant from the second bank.

4. The bus HVAC system of claim 3, wherein each of the microchannel heat exchangers has a top portion and a bottom portion, the inlet is configured to direct the refrigerant toward the top portion of the first bank of the microchannel heat exchanger and the outlet is configured to direct the refrigerant out of the second bank of the microchannel heat exchanger, and the first bank and the second bank forms fluid communication through the bottom portion of the microchannel heat exchanger.

5. The bus HVAC system of claim 1, wherein the microchannel heat exchanger includes a splitter configured to distribute refrigerant directed into the microchannel heat exchanger by the inlet, the splitter includes a flat plate with a plurality of apertures, and the splitter is configured to cover end openings of microchannel pipes of the microchannel heat exchanger.

6. The bus HVAC system of claim 5, wherein the splitter include a vertical structure extending from the flat plate in a direction that is substantially perpendicular to a flow direction of the refrigerant directed into the microchannel heat exchanger by the inlet.

7. The bus HVAC system of claim 6, wherein the vertical structure include a blocking portion and a flow through portion, the blocking portion is configured to block the refrigerant, and the flow through portion is configured to allow refrigerant to flow therethrough.

8. A microchannel heat exchanger, comprising:

9. The microchannel heat exchanger of claim 8, wherein each of the apertures is positioned between two neighboring microchannel pipes.

10. The microchannel heat exchanger of claim 8, wherein the splitter includes a first vertical structure rising from the fiat plate in a direction that is perpendicular to a flow direction of the refrigerant, the splitter includes a blocking portion and a flow through portion.

11. The microchannel heat exchanger of claim 10, wherein the splitter includes a second vertical structure rising from the flat plate in a direction that is substantially perpendicular to a flow direction of the refrigerant, the second vertical structure is further away from the inlet than the first vertical structure in a longitudinal direction.

12. The microchannel heat exchanger of claim 11 , wherein the second vertical structure includes a blocking portion and a flow through portion, the flow through portion of the second vertical structure is smaller in size than the flow through portion of the first vertical structure.

13. The microchannel heat exchanger of claim 8, comprising:

14. The microchannel heat exchanger of claim 13, wherein the first bank and a second bank form fluid communication at the bottom portion of the microchannel heat exchanger.

15. The microchannel heat exchanger of claim 13, comprising: