This invention relates generally to heat exchangers and, more particularly, to dual duty multiple tube bank heat exchanger for use in heating, ventilation, air conditioning and refrigeration (HVAC&R) systems.
Refrigerant vapor compression systems are well known in the art. Air conditioners and heat pumps employing refrigerant vapor compression cycles are commonly used for cooling or cooling/heating air supplied to a climate-controlled comfort zone within a residence, office building, hospital, school, restaurant or other facility. Refrigerant vapor compression systems are also commonly used for cooling air or other secondary fluid to provide a refrigerated environment for food items and beverage products within, for instance, display cases in supermarkets, convenience stores, groceries, cafeterias, restaurants and other food service establishments. In the case of refrigerated trucks, a transport refrigeration system is mounted behind or on the roof of the truck and is configured to maintain a controlled temperature environment within the cargo box of the truck. In the case of refrigerated trailers, which are typically pulled behind a tractor cab, a transport refrigeration system is mounted generally to the front wall of the trailer and is configured to maintain a controlled temperature environment within the cargo box of the trailer.
Commonly, these refrigerant vapor compression systems include a compression device, a refrigerant heat rejection heat exchanger, an expansion device and a refrigerant heat absorption heat exchanger connected in serial refrigerant flow communication in a refrigerant vapor compression cycle. In a subcritical refrigerant vapor compression cycle, the refrigerant heat rejection heat exchanger functions as a condenser. In a transcritical refrigerant vapor compression cycle, however, the refrigerant heat rejection heat exchanger functions as a gas cooler. In either a subcritical or transcritical refrigerant vapor compression cycle, the refrigerant heat absorption heat exchanger functions as an evaporator. Additionally, conventional refrigerant vapor compression systems sometimes include one or more refrigerant-to refrigerant heat exchangers, for example, an economizer heat exchanger or a suction line-to-liquid line heat exchanger, or air-to-refrigerant heat exchanger, such as a reheat heat exchanger, variable frequency drive cooler or an intercooler. Furthermore, if the refrigerant system is driven by an engine, other heat exchangers such radiator or turbo-charger/super-charger cooler may be included.
Historically, the refrigerant heat rejection heat exchanger and the refrigerant heat absorption heat exchanger used in such refrigerant vapor compression systems have been round tube and plate fin heat exchangers constituting a plurality of round tubes, disposed in a desired circuiting arrangement, with each circuit defining a refrigerant flow path extending between a pair of headers or manifolds. Thus, a round tube and plate fin heat exchanger with conventional round tubes will have a relatively small number of large flow area refrigerant flow paths extending between the headers.
More recently, flat, rectangular, racetrack, or oval shape, multi-channel tubes are being used in heat exchangers for refrigerant vapor compression systems. Sometimes, such multi-channel heat exchanger constructions are referred to as microchannel or minichannel heat exchangers as well. Each multi-channel tube has a plurality of flow channels extending longitudinally in parallel relationship the length of the tube, each channel defining a small cross-sectional flow area refrigerant path. Thus, a heat exchanger with multi-channel tubes extending in parallel relationship between a pair of headers or manifolds of the heat exchanger will define a relatively large number of small. cross-sectional flow area refrigerant paths extending between the two headers. To provide a multi-pass flow arrangement within a multi-channel heat exchanger core, the headers, which in some embodiments may be intermediate manifolds, may be divided into a number of chambers, which depends on a desired number of refrigerant passes.
Conventional refrigeration applications, such as a transport refrigeration system for example, include a plurality of separate heat exchangers. Each of these heat exchangers includes different design requirements and is manufactured separately prior to being installed into the heat exchanger assembly. These heat exchangers may be constructed as single slab micro-channel heat exchangers. As a result, the increased design complexity, additional components and installation time required to assemble and integrate the heat exchangers into the system increase the cost of the assembly significantly. Therefore a more simplified, cost effective and thermally advanced multiple duty heat exchanger is required.
An embodiment of the invention is provided including a heat exchanger having a first tube bank having at least a first and a second flattened tube segments extending longitudinally in spaced parallel relationship. A second tube bank includes at least a first group of flattened tube segments and a second group of flattened tube segments extending longitudinally in spaced parallel relationship. The second tube bank is disposed behind the first tube bank with a leading edge of the second tube bank spaced from a trailing edge of the first tube bank. The first group of flattened tube segments receives a first fluid. The second group of flattened tube segments receives a second fluid. A fan provides an airflow across the first tube bank and the second tube bank in sequence.
The subject matter, which is regarded as the invention, is particularly pointed out and distinctly claimed in the claims at the conclusion of the specification. The foregoing and other features, and advantages of the invention are apparent from the following detailed description taken in conjunction with the accompanying drawings in which:
The detailed description explains embodiments of the invention, together with advantages and features, by way of example with reference to the drawings.
Referring now to
The first tube bank 100, illustrated in
As illustrated in
Each set of manifolds 102, 202, 104, 204 disposed at either side of the heat exchanger 20 may comprise separate paired manifolds, may comprise separate chambers within an integral one-piece folded manifold assembly or may comprise separate chambers within an integral fabricated (e.g. extruded, drawn, rolled and welded) manifold assembly. Each tube bank 100, 200 may further include guard or “dummy” tubes (not shown) extending between its first and second manifolds at the top of the tube bank and at the bottom of the tube bank. These “dummy” tubes do not convey refrigerant flow, but add structural support to the tube bank and protect the uppermost and lowermost fins.
Referring now to
The interior flow passage of each of the heat exchange tube segments 106, 206 of the first and second tube banks 100, 200, respectively, may be divided by interior walls into a plurality of discrete flow channels 120, 220 that extend longitudinally over the length of the tube segment 106, 206 from an inlet end to an outlet end and establish fluid communication between the respective manifolds 102, 104, 202, 204 of the first and the second tube banks 100, 200. The heat exchange tube segments 206 of the second tube bank 200 may have a width substantially equal to or different from the width of the tube segments 106 of the first tube bank 100. Although the tube segments 206 of the second tube bank 200, illustrated in
The second tube bank 200, i.e. the rear heat exchanger slab, is disposed behind the first tube bank 100, i.e., the front heat exchanger slab, with respect to the airflow direction, with each heat exchange tube segment 106 directly aligned with a respective heat exchange tube segment 206 and with the leading edges 208 of the heat exchange tube segments 206 of the second tube bank 200 spaced from the trailing edges 110 of the heat exchange tube segments of the first tube bank 100 by a desired spacing, G. In embodiments where the tube segments 106 and 206 are fabricated separately and do not have the connecting web 40 (the web 40 typically would have the slots and end notches—not shown), a spacer or a plurality of spacers disposed at longitudinally spaced intervals may be provided between the trailing edges 110 of the heat exchange tube segments 106 and the leading edges 208 of the heat exchange tube segments 206 to maintain the desired spacing, G, during assembly and brazing of the preassembled heat exchanger 20 in a brazed furnace.
In the embodiment depicted in
Referring still to
In the depicted embodiment, the depth of each of the ribbon-like folded fin 320 extends at least from the leading edge 108 of the first tube bank 100 to the trailing edge of 210 of the second bank 200, and may overhang the leading edge 108 of the first tube bank 100 or/and trailing edge 208 of the second tube bank 200 if desired. Thus, when a folded fin 320 is installed between a set of adjacent multiple tube, flattened heat exchange tube assemblies, a first section 324 of each fin 322 is disposed within the first tube bank 100, a second section 326 of each fin 322 spans the spacing, G, between the trailing edge 110 of the first tube bank 100 and the leading edge 208 of the second tube bank 200, and a third section 328 of each fin 322 is disposed within the second tube bank 200. In an embodiment, each fin 322 of the folded fin 320 may be provided with louvers 330, 332 formed in the first and third sections, respectively, of each fin 322.
Referring now to
Referring now to
The first fluid is configured to pass through the heat exchanger 20 in a cross-counterflow arrangement relative to the airflow, in that the first fluid provided to chamber 203 of manifold 202 via an inlet 221 passes through the first portion 206a of tube segments 206 of the second tube bank 200 to chamber 207 of the second manifold 204. Chamber 207 of the second manifolds 204 of the second tube bank 200 is fluidly coupled to the second manifold 104 of the first tube bank 100 such that the first fluid flows from the second tube bank 200 to the first tube bank 100 and then through at least a portion of the tube segments 106 of the first tube bank 100. The first fluid may be configured to flow through the first tube bank 100 in a single pass configuration indicated by arrow 402 (
The second fluid is configured to pass through the second tube bank 100 in a cross-flow arrangement relative to the airflow, indicated by arrow 405. The second fluid passes into the chamber 205 of manifold 202 of the second tube bank 200 through at least one inlet 223. From manifold 202, the second fluid flows through the second portion 206b of heat exchange tube segments 206, to chamber 209 of the second manifold 204 and outlet 222. As the fluids pass simultaneously through the second tube bank 200, the first fluid and the second fluid are approximately at the same temperature to minimize the cross-conduction effect, and therefore improve the performance of the heat exchanger 20. Although the first tube bank 100 and the second tube bank 200 are depicted with a certain flow configuration relative to the air flow A, other configurations are within the scope of the invention.
The multiple bank flattened tube finned heat exchanger 20 may be integrated into a refrigeration system to improve the overall efficiency of the system. Referring now to
The TRU 505 functions in a conventional manner to establish and regulate a desired product storage temperature within the refrigerated cargo space wherein perishable products, such as food, pharmaceuticals, and other temperature sensitive cargo for example, are stowed for transport. The TRU 505 includes a refrigeration compression device 515, a heat rejection heat exchanger 520, an expansion device 525, and a heat absorption heat exchanger 530 connected to form a closed loop refrigeration circuit. The TRU 505 also includes one or more fans 540, 545 associated with the heat rejection heat exchanger 520 and the heat absorption heat exchanger 530 respectively. In the illustrated, non-limiting embodiment, the heat rejection heat exchanger 520 is a multiple bank flattened tube finned heat exchanger 20.
The heat rejection heat exchanger 520 is also fluidly coupled to a second fluid circuit, such as a coolant circuit of the prime mover 510 for example. The heat rejection heat exchanger 520 may be configured to function in a manner similar to a radiator to reject the heat absorbed by the coolant from the prime mover 510. A pump 550 circulates coolant between the prime mover 510 and the heat rejection heat exchanger 520. Although a particular configuration of a transportation refrigeration system 500 is illustrated and described herein, other fluid circuits, such as of a turbocharger, a variable frequency drive, or another auxiliary unit for example, may be fluidly and thermally coupled at a multiple bank flattened tube finned heat exchanger 20.
Referring again to the heat exchanger in
Coolant from the coolant circuit may be provided through inlet 223 to chamber 205 of the first manifold 202 of the second tube bank 200. The coolant C passes through the second portion 206b of the heat exchange tube segments 206 to chamber 209 of the second manifold 204, from where the coolant C is returned to the coolant circuit through at least one outlet 222. The coolant C in the second portion 206b of heat exchanger tube segments 206 may be configured to flow in either a single-pass or multi-pass flow arrangement.
In the described embodiment, the first portion 206a of tube segments 206 of the second tube bank 200 is configured to de-superheat and initiate condensing of the refrigerant R and the second portion 206b of tube segments 206 of the second tube bank 200 is configured to cool the coolant C in place of a separate radiator. The first tube bank 100 of the heat exchanger 20 is dedicated to the condensing and sub-cooling of the refrigerant R. Such an arrangement prevents cross-conduction from the second slab 200 to the first slab 100, since hot desuperheating refrigerant R and hot engine coolant C are contained within the second slab 200 and have limited cross-conduction connection to the relatively cool condensing and subcooling refrigerant within the first slab 100. Other configurations where the flow of refrigerant R and coolant C through a multiple bank flattened tube finned heat exchanger 20 are reversed and still be considered within the scope of the invention.
In another embodiment, illustrated in
One configuration of the heat rejection heat exchanger 520 of the transport refrigeration system 500 of
Another configuration of the heat rejection heat exchanger 520 of the transport refrigeration system 500 of
In the illustrated, non-limiting embodiment, the intercooler refrigerant Ri from the first compressor 515 is provided through an inlet 136 to a chamber 128 of the second manifold 104 of the first tube bank 100. The intercooler refrigerant Ri is configured to flow through the second, upper portion 106b of heat exchange tube segments 106 to chamber 132 of the first manifold 102. From the first manifold 102, the intercooler refrigerant is returned to the refrigerant system via outlet 138.
By integrating two or more fluid circuits into a multiple bank flattened fin heat exchanger 20, the manufacturing and logistical complexity of the fluid circuits is greatly reduced. In addition, integration of two previously separate heat exchangers into a single multiple bank flattened fin heat exchanger 20 results in improved corrosion durability and a significant cost reduction. It is understood that the invention can be applied to any other portable or engine driven system where another auxiliary heat exchanger is utilized to reject heat.
While the present invention has been particularly shown and described with reference to the exemplary embodiments as illustrated in the drawing, it will be recognized by those skilled in the art that various modifications may be made without departing from the spirit and scope of the invention. Therefore, it is intended that the present disclosure not be limited to the particular embodiment(s) disclosed as, but that the disclosure will include all embodiments falling within the scope of the appended claims. In particular, similar principals and ratios may be extended to the rooftops/chiller applications as well as vertical package units.
This application claims the benefit of U.S. provisional patent application Ser. No. 61/908,265 filed Nov. 25, 2013, the entire contents of which are incorporated herein by reference.
Filing Document | Filing Date | Country | Kind |
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PCT/US2014/057147 | 9/24/2014 | WO | 00 |
Number | Date | Country | |
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61908265 | Nov 2013 | US |