HK1169702A - Hybrid serial counterflow dual refrigerant circuit chiller - Google Patents

Description

Hybrid continuous counter-flow dual refrigerant loop cooler

Technical Field

The present invention relates generally to a dual circuit chiller and more particularly to improvements in the water side performance of a dual refrigerant circuit chiller.

Background

Chillers are well known for providing a chilled fluid, typically water or brine, for use in air conditioning systems of buildings, particularly large commercial buildings. A common type of cooler includes: a shell and tube heat exchanger functioning as a refrigerant vapor condenser; a shell and tube heat exchanger functioning as a refrigerant liquid evaporator; and a centrifugal compressor having an inlet in refrigerant flow communication with the evaporator and an outlet in refrigerant flow communication with the condenser. In the condenser, a cooling fluid (most commonly water) flows through heat exchange tubes in heat exchange relationship with hot refrigerant vapor discharged from the compressor into the shell of the condenser and flowing over the heat exchange tubes. In doing so, the refrigerant vapor is condensed and the water flowing through the heat exchange tubes is heated. The condensed liquid refrigerant passes through an expansion device and is expanded thereby to form a lower pressure, lower temperature refrigerant liquid/vapor mixture. The refrigerant liquid/vapor mixture is delivered into the shell of the evaporator and diffused to flow over the heat exchange tubes in the shell of the evaporator. In the evaporator, the water flowing through the heat exchange tubes is cooled and the refrigerant liquid/vapor mixture is heated, whereby the liquid refrigerant evaporates. The refrigerant vapor exits the shell of the evaporator and flows back to the inlet of the compressor, thereby completing the refrigerant flow cycle. The cooled water that has passed through the evaporator heat exchange tubes is delivered to a building air conditioning system for cooling air to be supplied to one or more climate controlled spaces within the building.

In one type of chiller, commonly referred to as a once-through single-circuit chiller, a single water-cooled condenser, a single centrifugal compressor, and a single chilled water evaporator are connected in a single refrigerant circuit, as described above. In the condenser, a plurality of parallel water transport tubes extend longitudinally parallel to the axis of the condenser shell in a single pass configuration. Similarly, in the evaporator, a plurality of parallel water transport tubes extend longitudinally parallel to the axis of the condenser in a single pass configuration. Typically, the water to be cooled flowing through the once-through tubes of the evaporator flows in countercurrent relationship to the cooling water flowing through the once-through tubes of the condenser. However, the ability to cool water that can be achieved using a single-pass single-circuit cooler is limited.

One way to increase the cooling water capacity is to provide a dual-circuit chiller consisting of two single-pass single-circuit chillers arranged with their respective refrigerant circuits in parallel and with the water flow path of the respective condenser and the water flow path of the respective evaporator connected in a continuous relationship. Again, the water to be cooled flowing through the once-through tubes of the evaporator flows in countercurrent relationship to the cooling water flowing through the once-through tubes of the condenser. Thus, the water to be cooled flows first through the condenser associated with the first refrigerant circuit and then through the condenser associated with the second refrigerant circuit, but the cooling water flows first through the evaporator associated with the second refrigerant circuit and then through the evaporator associated with the first refrigerant circuit.

Disclosure of Invention

In one aspect of the invention, a dual refrigerant circuit chiller is provided having: a first refrigerant circuit including a first condenser and a first evaporator; a second refrigerant circuit including a second condenser and a second evaporator; a condenser assembly comprising a first condenser and a second condenser interconnected in a continuous cooling fluid circuit; an evaporator assembly comprising a first evaporator and a second evaporator interconnected in a continuous fluid circuit; and a water tank disposed between the first evaporator and the second evaporator. The condenser assembly has a cooling fluid inlet in fluid communication with the second condenser and a cooling fluid outlet in fluid communication with the first condenser. The evaporator assembly has a circuit fluid inlet in fluid communication with the first evaporator and a circuit fluid outlet in fluid communication with the second evaporator. The circuit fluid inlet and the circuit fluid outlet are disposed at opposite longitudinal ends of the evaporator assembly. In one embodiment, the first evaporator has a multi-pass circuit fluid-to-refrigerant heat exchanger having an outlet in fluid communication with the waterbox and an inlet in fluid communication with the circuit fluid inlet of the evaporator assembly, and the second evaporator has a multi-pass circuit fluid-to-refrigerant heat exchanger having an inlet in fluid communication with the waterbox and an outlet in fluid communication with the circuit fluid outlet of the evaporator assembly. In one embodiment, the loop fluid-to-refrigerant heat exchanger of the first evaporator and the loop fluid-to-refrigerant heat exchanger of the second evaporator each comprise a three pass tube bundle heat exchanger.

In one aspect of the invention, a dual circuit chiller is provided having: a first refrigerant circuit including a first condenser and a first evaporator; a second refrigerant circuit including a second condenser and a second evaporator; a condenser assembly comprising a first condenser and a second condenser interconnected in a continuous cooling fluid circuit, wherein a cooling fluid inlet is in fluid communication with the second condenser and a cooling fluid outlet is in fluid communication with the first condenser; an evaporator assembly, the condenser assembly including first and second evaporators interconnected in a continuous fluid circuit and a water tank disposed intermediate the first and second evaporators, the water tank having first, second and third chambers. The evaporator assembly has: a circuit fluid inlet and a circuit fluid outlet disposed at opposite longitudinal ends of the evaporator assembly; a first bypass conduit having an inlet in fluid communication with the circuit fluid inlet of the evaporator assembly and an outlet in fluid communication with the first chamber of the waterbox; a first multi-pass circuit fluid to refrigerant heat exchanger disposed in the first evaporator, the first multi-pass circuit fluid to refrigerant heat exchanger having an inlet in fluid communication with the first chamber of the waterbox and an outlet in fluid communication with the second chamber of the waterbox; a second bypass conduit having an outlet in fluid communication with the loop fluid outlet of the evaporator assembly and an inlet in fluid communication with the third chamber of the waterbox; and a second multi-pass circuit fluid-to-refrigerant heat exchanger of the second evaporator, the second multi-pass circuit fluid-to-refrigerant heat exchanger having an inlet in fluid communication with the second chamber of the waterbox and an outlet in fluid communication with the third chamber of the waterbox.

In either embodiment, the cooling fluid may be cooling water and the loop fluid may be chiller water. In either embodiment, the cooling fluid may be cooling water and the loop fluid may be chiller brine. Additionally, in any embodiment, the condenser assembly may further comprise: a water tank disposed between the first condenser and the second condenser; a multi-pass cooling fluid to refrigerant heat exchanger in the second condenser, the heat exchanger having an outlet in fluid communication with the waterbox and an inlet in fluid communication with the cooling fluid inlet of the condenser assembly; and a multi-pass cooling fluid to refrigerant heat exchanger in the first condenser, the heat exchanger having an inlet in fluid communication with the waterbox and an outlet in fluid communication with the cooling fluid outlet of the condenser assembly, wherein the cooling fluid inlet and the cooling fluid outlet are disposed at opposite longitudinal ends of the condenser assembly.

Drawings

For a further understanding of the disclosure, reference should be made to the following detailed description, read in conjunction with the accompanying drawings, in which

FIG. 1 is a perspective plan view of an exemplary embodiment of a dual circuit chiller according to one aspect of the present invention applied to an evaporator water circuit;

FIG. 2 is a perspective elevation view of the dual circuit chiller of FIG. 1;

FIG. 3 is a schematic diagram of the refrigerant circuit of the embodiment of the dual circuit chiller shown in FIG. 1;

FIG. 4 is a schematic diagram of the condenser water-side loop and the evaporator water-side loop of the embodiment of the dual-loop cooler shown in FIG. 1;

FIG. 5 is a cross-sectional elevation view taken along line 5-5 of FIG. 4;

FIG. 6 is a cross-sectional elevation view taken along line 6-6 of FIG. 4;

FIG. 7 is a schematic diagram of a condenser water-side circuit and an evaporator water-side circuit of another exemplary embodiment of a dual circuit chiller according to an aspect of the present invention;

FIG. 8 is a cross-sectional elevation view taken along line 8-8 of FIG. 7;

FIGS. 9A and 9B are cross-sectional elevation views taken along lines 9A-9A and 9B-9B of FIG. 7, respectively;

FIG. 10 is a schematic diagram of a condenser water-side circuit and an evaporator water-side circuit of another exemplary embodiment of a dual circuit chiller according to an aspect of the present invention;

FIG. 11 is a cross-sectional elevation view taken along line 11-11 of FIG. 7;

FIG. 12 is a schematic diagram of an evaporator waterside circuit of another exemplary embodiment of a dual circuit chiller according to an aspect of the present invention;

FIG. 13 is a cross-sectional elevation view taken along line 13-13 of FIG. 12;

FIG. 14 is a cross-sectional elevation view taken along line 14-14 of FIG. 12;

FIG. 15 is a cross-sectional elevation view taken along line 15-15 of FIG. 12;

FIG. 16 is a cross-sectional elevation view taken along line 16-16 of FIG. 12;

FIG. 17 is a plan view of the embodiment of the intermediate tank shown in FIG. 12;

FIG. 18 is a perspective view of an alternative embodiment of the intermediate waterbox of the embodiment of the dual refrigerant circuit chiller shown in FIG. 12;

FIG. 19 is a schematic diagram of an evaporator waterside circuit of another exemplary embodiment of a dual circuit chiller according to an aspect of the present invention;

FIG. 20 is a plan view of the embodiment of the intermediate tank shown in FIG. 19;

FIG. 21 is a cross-sectional elevation view taken along line 21-21 of FIG. 19;

FIG. 22 is a cross-sectional elevation view taken along line 21-21 of FIG. 19;

FIG. 23 is a cross-sectional elevation view taken along line 21-21 of FIG. 19;

FIG. 24 is a cross-sectional elevation view taken along line 24-24 of FIG. 19;

fig. 25 is a perspective view illustrating an intermediate tank of the embodiment of the dual refrigerant circuit cooler shown in fig. 19.

Detailed Description

Referring initially to fig. 1-4, 7 and 10 of the drawings, and in particular, there is shown an exemplary embodiment of a compressor 10 having two independent refrigerant circuits 100, 200 disposed in parallel refrigerant flow relationship, the compressor 10 being generally referred to and herein as a dual circuit cooler. The cooler 10 includes a water-cooled condenser 30, a cooling water evaporator 40, and a pair of refrigerant vapor compressors 120, 220. The refrigerant vapor compressor 120, 220 may be a centrifugal compressor. Separate drive motors 122, 222 may be provided in operative association with the first and second compressors 120, 220, respectively. The first driving motor 122 drives only the first compressor 120. The second driving motor 222 drives only the second compressor 220.

The condenser 30 includes a first condenser 130 and a second condenser 230 disposed in a continuous water flow relationship. Each of the first condenser 130 and the second condenser 230 comprises a shell-and-tube heat exchanger that cools the fluid to the refrigerant having a plurality of heat exchange tubes disposed within a longitudinally extending closed cylindrical shell. The distal ends of the first and second condensers 130, 230 are closed by end caps l34, 234, respectively, and end caps l34, 234 are mounted to the tube sheets 136, 236, respectively. In the embodiment of the cooler 10 shown in fig. 1-4, the proximal end of the first condenser 130 and the proximal end of the second condenser 230 are connected to each other at respective tube sheets 32. However, in the embodiment of the cooler 10 shown in fig. 7 and 10, the proximal ends of the first and second condensers 130, 230 are interconnected to the waterbox 60 disposed between the respective tube sheets 32 of the first and second condensers 130, 230.

The evaporator 40 includes a first evaporator 140 and a second evaporator 240 disposed in a continuous water flow relationship. Each of the first evaporator 140 and the second evaporator 240 comprises a loop fluid to refrigerant shell and tube heat exchanger having a plurality of heat exchange tubes disposed within a longitudinally extending closed cylindrical shell. The distal ends of the first and second evaporators 140, 240 are closed by end caps l44, 244, respectively, and end caps l44, 244 are mounted to the tube sheets 146, 246, respectively. The proximal end of the first evaporator 140 and the proximal end of the second evaporator 240 are interconnected to a waterbox 50 disposed between the respective tube sheets 42 of the first and second evaporators 140, 240.

As previously described, the dual circuit cooler 10 has two independent refrigerant circuits 100, 200 arranged in parallel relationship. The first refrigerant circuit 100 includes a first compressor 120, a first condenser 130, and a first evaporator 140. In operation, high pressure, high temperature refrigerant vapor is discharged from the first compressor 120 into the shell of the first condenser 130 via the discharge line 124. The high temperature and high pressure refrigerant vapor introduced into the shell of the first condenser 130 passes over the exterior of the heat exchange tubes within the shell in heat exchange relationship with the cooling water flowing through the heat exchange tubes, whereby the refrigerant vapor is cooled and condensed into a high pressure refrigerant liquid, while the cooling water is heated. The high pressure condensed refrigerant liquid flows from the first condenser 130 to the first evaporator 140 via the refrigerant passage 111 in which the expansion device 125 is disposed.

As the high pressure refrigerant liquid flows through the expansion device 125, the refrigerant liquid expands to a lower pressure and lower temperature to most typically form a saturated mixture of refrigerant liquid and refrigerant vapor at the lower pressure and lower temperature. The lower pressure, lower temperature liquid/vapor mixture is delivered via passage 111 and introduced into the shell of first evaporator 140. The lower temperature refrigerant liquid accumulates in the shell to at least partially submerge the heat exchange tubes of the first evaporator 140. Thus, the cooler water flowing through the heat exchange tubes of the first evaporator 140 flows in heat exchange relationship with the refrigerant introduced into the shell of the first evaporator 140, whereby the refrigerant liquid is heated and evaporated to refrigerant vapor, while the cooler water is cooled. Low pressure, low temperature refrigerant vapor passes from the first evaporator through a suction line 126 back to the suction inlet of the first compressor 120.

The second refrigerant circuit 200 includes a second compressor 220, a second condenser 230, and a second evaporator 240. In operation, high pressure, high temperature refrigerant vapor is discharged from the second compressor 220 into the shell of the second condenser 230 via discharge line 224. The high-pressure, high-temperature refrigerant vapor introduced into the shell of the second condenser 230 passes over the exterior of the heat exchange tubes within the shell in heat exchange relationship with the cooling water flowing through the heat exchange tubes, whereby the refrigerant vapor is cooled and condensed into a high-pressure refrigerant liquid, while the cooling water is heated. The high pressure, condensed refrigerant liquid flows from the second condenser 230 to the second evaporator 240 via the refrigerant passage 211 having the expansion device 225 disposed therein.

As the high pressure refrigerant liquid flows through the expansion device 125, the refrigerant liquid expands to a lower pressure and lower temperature to most typically form a saturated mixture of refrigerant liquid and refrigerant vapor at the lower pressure and lower temperature. The lower pressure, lower temperature liquid/vapor mixture is delivered via refrigerant passage 211 and directed into the shell of second evaporator 240. The lower temperature refrigerant liquid accumulates in the shell to at least partially submerge the heat exchange tubes of the second evaporator 240. Thus, the cooler water flowing through the heat exchange tubes of the second evaporator 240 flows in heat exchange relationship with the refrigerant introduced into the shell of the second evaporator 240, whereby the refrigerant liquid is heated and evaporated to refrigerant vapor, while the chilled water is cooled. Low pressure, low temperature refrigerant vapor passes from the second evaporator 240 through suction line 226 back to the suction inlet of the second compressor 220.

In the embodiment shown in fig. 4, the heat exchange tubes of the first and second condensers 130, 230 are arranged in a single pass configuration. The condenser cooling water enters the condenser 230 via a cooling water inlet 33, the cooling water inlet 33 opening into an inlet chamber 31 defined within an end cap 234, and the cooling water then flows successively first through the tubes of the second condenser 230 and then through the tubes of the first condenser 130 into an outlet chamber 37 defined within an end cap 134 of the first condenser 130. The cooling water flows out of the outlet chamber 37 via the cooling water outlet 35. Therefore, with respect to the flow of the cooling water, the second condenser 230, which is a part of the second coolant circuit 200, constitutes an upstream condenser, and the first condenser 130, which is a part of the first refrigerant circuit 100, constitutes a downstream condenser.

The cooler water, which is water to be cooled, flows into the evaporator 40 via the cooler water inlet 45 of the first evaporator 140, and flows out of the evaporator 40 via the cooler water outlet 43 of the second evaporator 240. Thus, with respect to the chiller water flow, the first evaporator 140, which is part of the first refrigerant circuit 100, constitutes an upstream evaporator, and the second evaporator 240, which is part of the second refrigerant circuit 200, constitutes a downstream evaporator. Thus, the chiller water flows through the evaporator 40 in countercurrent relationship to the condenser water flowing through the condenser 30. In the flow of the cooler water from the inlet chamber 41 defined in the end cover 144 of the first evaporator 140 to the outlet chamber 47 defined in the end cover 244 of the second evaporator 240, the cooler water does not flow through a single-pass path as in a typical conventional dual-circuit cooler.

In the refrigerant 10 of the present invention, however, the cooler water flowing through the heat exchange tubes of the evaporator 40 flows through a multi-pass path in heat exchange relationship with the refrigerant in the evaporator 40. As shown in fig. 4, 7, and 10, in the cooler 10, the waterbox 50 is disposed between the respective tube sheets 42 of the first and second evaporators 140, 240. The water tank 50 is divided by inner walls 52, 54 into three chambers, a first chamber 51, a second chamber 53 and a third chamber 55.

In the embodiment shown in fig. 4 and 10, the heat exchange tubes of the first pass tube bundle 171 of the first evaporator 140 connect the inlet chamber 41 of the evaporator 40 in fluid communication with the first chamber 51 of the waterbox 50. The heat exchange tubes of the second pass tube bundle 172 of the first evaporator 140 connect the first chamber 51 of the waterbox 50 in fluid communication with the intermediate chamber 141 of the first evaporator 140. The heat exchange tubes of the third pass tube bundle 173 of the first evaporator 140 connect the intermediate chamber 141 in fluid communication with the second chamber 53 of the waterbox 50. The heat exchange tubes of the first pass tube bundle 271 of the second evaporator 240 connect the intermediate chamber 53 of the waterbox 50 in fluid communication with the intermediate chamber 247 of the second evaporator 240. The heat exchange tubes of the second pass tube bundle 272 of the second evaporator 240 connect the intermediate chamber 247 of the second evaporator 140 in fluid communication with the third chamber 55 of the waterbox 50. The heat exchange tubes of the third pass tube bundle 273 of the second evaporator 240 connect the third chamber 55 of the waterbox 50 in fluid communication with the outlet chamber 47 of the second evaporator 240. Thus, in the embodiment shown in fig. 4 and 10, the cooler water flowing through the evaporator 40 passes through multiple passes in each of the first and second evaporators 140, 240 in heat exchange relationship with the refrigerant therein.

In the embodiment of the cooler 10 shown in fig. 7 and 10, the waterbox 60 is also disposed between the respective tube sheets 32 of the first and second condensers 130, 230. The water tank 60 is divided by inner walls 62, 64 into three chambers, a first chamber 61, a second chamber 63 and a third chamber 65. The condenser cooling water flows into the condenser 30 via the cooling water inlet 33 of the second condenser 230 and out of the condenser 30 via the cooling water outlet 35 of the first condenser 130, and flows through the multi-pass path as the cooling water flows through the condenser 30 in heat exchange relationship with the refrigerant.

In this multi-pass arrangement of the condenser 30, as shown in fig. 7 and 10, the heat exchange tubes of the first-pass tube bundle 281 of the second evaporator condenser 230 connect the inlet chamber 31 of the condenser 30 in fluid communication with the first chamber 61 of the waterbox 60. The heat exchange tubes of the second pass tube bundle 282 of the second condenser 230 connect the first chamber 61 of the waterbox 60 in fluid communication with the intermediate chamber 231 of the second condenser 230. The heat exchange tubes of the second pass tube bundle 282 of the second condenser 230 connect the first chamber 61 of the waterbox 60 in fluid communication with the intermediate chamber 231 of the second condenser 230. The heat exchange tubes of the third pass tube bundle 283 of the second condenser 230 connect the intermediate chamber 231 in fluid communication with the second chamber 63 of the waterbox 60. The heat exchange tubes of first pass tube bundle 181 of first condenser 130 connect intermediate chamber 63 of waterbox 60 and intermediate chamber 137 of first condenser 130 in fluid communication. The heat exchange tubes of the second pass tube bundle 182 of the first condenser 130 connect the intermediate chamber 137 of the first condenser 130 in fluid communication with the third chamber 65 of the waterbox 60. The heat exchange tubes of the third pass tube bundle 183 of the first condenser 130 connect the third chamber 65 of the waterbox 60 in fluid communication with the outlet chamber 37 of the first condenser 130. Thus, in the embodiment illustrated in fig. 4 and 8, the cooling water flowing through the condenser 30 passes through multiple passes in each of the first and second condensers 130, 230 in heat exchange relationship with the refrigerant therein.

Referring now to fig. 7, 9A and 9B, in particular, in the embodiment of the chiller 10 shown therein, the chiller water flows into the evaporator 40 via a first bypass duct 190, the first bypass duct 190 extending longitudinally from the chiller water inlet via the first evaporator 140 to be in fluid communication with the first chamber 51 of the tank 50. The cooler water exits the evaporator 40 via a second bypass conduit 290, which second bypass conduit 290 extends longitudinally to the cooler water outlet via the second evaporator 240 in fluid communication with the third chamber 55 of the waterbox 50. Between the first chamber 51 of the water tank 50 and the third chamber of the water tank 50, the cooler water flows through the two-pass heat exchanger in the first evaporator 140, through the second chamber 53 of the water tank 50, and then through the two-pass heat exchanger in the second evaporator 240. The heat exchange tubes of the second pass tube bundle 172 of the first evaporator 140 connect the first chamber 51 of the waterbox 50 and the intermediate chamber 141 of the first evaporator 140 in liquid communication. The heat exchange tubes of the third pass tube bundle 173 of the first evaporator 140 connect the intermediate chamber 141 in fluid communication with the second chamber 53 of the waterbox 50. The heat exchange tubes of the first pass tube bundle 271 of the second evaporator 240 connect the intermediate chamber 53 of the waterbox 50 in fluid communication with the intermediate chamber 247 of the second evaporator 240. The heat exchange tubes of the second pass tube bundle 272 of the second evaporator 240 connect the intermediate chamber 247 of the second evaporator 240 in fluid communication with the third chamber 55 of the waterbox 50.

Thus, in the embodiment shown in fig. 7, the chiller water flowing through the evaporator 40 passes through two passes in each of the first and second evaporators 140, 240 in heat exchange relationship with the refrigerant therein, rather than the three passes shown in fig. 4 and 10. Thus, after the cooler water enters the evaporator 40 via the bypass conduit 190, the tube bundle is substantially bypassed before flowing into the first chamber 51 of the waterbox 50 upon passing through the first evaporator 140, and the cooler water substantially bypasses the other tube bundle after exiting the third chamber 55 of the waterbox 50 upon exiting the evaporator 40 upon passing through the second evaporator 240 via the bypass conduit 290. Since the bypass conduits 190, 290 provide direct water flow paths between the cooler water inlet 45 and the first chamber 51 of the waterbox 50 and between the third chamber 55 of the waterbox 50 and the cooler water outlet 43, respectively, and since the bypass conduits 190, 290 have an inner diameter that is much larger than the inner diameter of the individual heat exchange tubes of the tube bundle, the water side pressure drop through the evaporator 40 of the embodiment of fig. 7 is greatly reduced compared to the water side pressure drop associated with three tube bundle passes in the evaporator 40 of the embodiment as shown in fig. 7 and 10. The bypass pipes 190, 290 are used to directly receive and discharge the cooler water into and from the evaporator water tank 50, respectively, and this use of the bypass pipes 190, 290 allows the bypass pipe 190 to be directly connected to a cooler water return pipe (not shown) of a user, and allows the bypass pipe 290 to be directly connected to a cooler water supply pipe (not shown) of the user. In this embodiment, since the bypass conduits 190 and 290 do not lead to or through each end tank 48, the heat exchange tubes of the tube bundles 172, 173, 271, 272 can be serviced and removed, if desired, by simply removing the covers of the appropriate end tanks, without having to remove the evaporator from the customer's chiller water system.

In the embodiment of the dual refrigerant loop cooler 10 shown in fig. 4, each condenser 130, 230 has a single pass cooling water side loop and each evaporator 140, 240 has a three pass cooler water side loop. In the embodiment of the dual refrigerant loop cooler 10 shown in fig. 7, each condenser 130, 230 has a three pass cooling water side loop and each evaporator 140, 240 has a two pass cooler water side loop. In the embodiment of the dual refrigerant loop cooler 10 shown in fig. 10, each condenser 130, 230 has a three pass cooling water side loop and each evaporator 140, 240 has a three pass cooler water side loop. In each of these configurations, cooling water enters the condenser 30 via one end cap and exits the condenser 30 via the other end cap. Similarly, the cooler water enters the evaporator 40 via one end cap and exits the evaporator 40 via the other end cap. In this manner, a continuous counter-flow relationship between the flow of condensate water and the flow of cooler water is maintained, even if the cooler water circuit in the evaporator is multi-pass in configuration. Additionally, on the condenser side, the chilled water side loop may be single pass or multiple pass while still maintaining a continuous flow arrangement through the condenser.

Referring now to fig. 12-18, specifically, in the embodiment of the evaporator 40 of the chiller 10 shown in the figures, the heat exchange tubes of the first pass tube bundle 371 of the first evaporator 140 connect the inlet chamber 341 of the first evaporator 140 in fluid communication with the first chamber 151 of the waterbox 150. The heat exchange tubes of the second pass tube bundle 372 of the first evaporator 140 connect the first chamber 151 of the waterbox 150 in fluid communication with the intermediate chamber 343 of the end cap of the first evaporator 140. The heat exchange tubes of the bypass tube 390 of the first evaporator 140 connect the intermediate chamber 343 in fluid communication with the second chamber 153 of the waterbox 150. The heat exchange tubes of the first pass tube bundle 274 of the second evaporator 240 connect the second chamber 153 of the waterbox 150 in fluid communication with the intermediate chamber 345 of the end cap of the second evaporator 240. The heat exchange tubes of the second pass tube bundle 375 of the second evaporator 240 connect the intermediate chamber 345 of the second evaporator 240 in fluid communication with the third chamber 155 of the waterbox 150. The heat exchange tubes of the bypass conduit 690 of the second evaporator 240 connect the third chamber 155 of the waterbox 150 in fluid communication with the outlet chamber 347 of the second evaporator 240.

In this embodiment, as shown in fig. 12 and 17, the water tank 150 is used for cooler water to flow through the second chamber 153 in a generally vertical flow. Thus, the cooler water enters the upper region of the second chamber 153 from the bypass conduit 390 of the first evaporator 140 and exits the waterbox 150 at the lower region of the second chamber 153 into the first pass tube bundle 374 of the second evaporator 240. Thus, as the cooler water transitions from the first evaporator 140 to the second evaporator 240 via the waterbox 150, the cooler water is delivered to the lower tube bundle 374 of the second evaporator 240. As shown in fig. 18, an alternative embodiment of the waterbox 150 provides a vertical path for the cooler water to transition from the first evaporator 140 to the second evaporator 240. As shown, a pair of inner walls 152 divide the interior of the water tank 150 into a first chamber 151, a second chamber 153, and a third chamber 155. As described with reference to fig. 12, each tube bundle pass 371, 372, 374, 375 and bypass conduit 390, 690 leads to the waterbox 150, wherein the second chamber 153 provides a vertical transition path.

Referring now to fig. 19-25, specifically, in the embodiment of the evaporator of the chiller 10 shown in the figures, the chiller water flows into the evaporator 40 via a first bypass conduit 490, the first bypass conduit 490 extending longitudinally from the chiller water inlet via the first evaporator 140 to be in fluid communication with the first chamber 251 of the tank 250. The cooler water exits the evaporator 40 via a second bypass conduit 590, the second bypass conduit 590 extending longitudinally to the cooler water outlet via the second evaporator 240 in fluid communication with the third chamber 255 of the water tank 250. Between the first chamber 251 of the water tank 250 and the third chamber 255 of the water tank 250, the cooler water flows through the two-pass heat exchanger in the first evaporator 140, through the second chamber 253 of the water tank 250, and then through the two-pass heat exchanger in the second evaporator 240. The heat exchange tubes of the second pass tube bundle 472 of the first evaporator 140 connect the first chamber 251 of the waterbox 250 in fluid communication with the end waterbox 448 of the first evaporator 140. The heat exchange tubes of the third pass tube bundle 473 of the first evaporator 140 connect the end waterbox 448 in fluid communication with the second chamber 253 of the waterbox 250. The heat exchange tubes of the first pass tube bundle 474 of the second evaporator 240 connect the intermediate chamber 253 of the waterbox 250 in fluid communication with the end waterbox 448 of the second evaporator 240. The heat exchange tubes of the second pass tube bundle 475 of the second evaporator 240 connect the end waterbox 448 of the second evaporator 240 in fluid communication with the third chamber 255 of the waterbox 250.

In the evaporator embodiment of the chiller 10 shown in FIG. 19, the bypass conduits 490, 590 do not lead to or through each of the end waterboxes 448, but instead taper away from the evaporator 40 outside of the end waterboxes 448 in a manner similar to the bypass conduits 190, 290 shown in the FIG. 7 embodiment of the chiller 10. Thus, as previously described with reference to the embodiment of FIG. 7, maintenance and removal of the heat exchange tubes of the various tube bundles within the evaporator 40 can be performed, if desired, simply by removing the covers of the appropriate end waterboxes 448 without having to remove the evaporator 40 from the user's chiller water system. It should be understood that the condenser 30 may also be constructed in a manner similar to that described with reference to the evaporator 40 shown in fig. 12 and 19.

It should be understood that for simplicity of illustration, the individual tube bundles of the shell-and-tube heat exchanger in the condenser and evaporator are shown as single tubes in fig. 4, 7, 10, 12 and 19 to illustrate the flow path of the water and are shown in cross-sectional profiles in fig. 5, 6, 8, 13, 14, 15, 16, 21, 22, 23 and 24. In practice, each tube bundle 171, 172, 173, 271, 272, 273, 281, 282, 283, 371, 372, 374, 375, 472, 473, 474, 475 includes a plurality of individual heat exchange tubes, typically hundreds, extending in parallel relationship between the tubesheet of each condenser and each evaporator, such as described with reference to tube bundles 172, 173, 271, 272 in fig. 9A and 9B. Each bypass duct 190, 290, 390, 490, 590, 690 defines a fluid passageway of a large flow area comparable to the flow area defined by the individual tubes of the tube bundle.

Although the chiller 10 is described herein with water as the condenser cooling fluid and water as the loop fluid to be chilled, those skilled in the art will recognize that fluids other than water may be used as the loop fluid and/or cooling fluid in the refrigerant dual loop chiller described above and in the appended claims. As an example, in one embodiment, the loop fluid may be chiller brine.

The terminology used herein is for the purpose of description and not of limitation. Specific structural and functional details disclosed herein are not to be interpreted as limiting, but merely as a basis for teaching one skilled in the art to utilize the present invention. While the present invention has been particularly shown and described with reference to the exemplary embodiments shown in the drawings, it will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention. It should also be appreciated by those of ordinary skill in the art that equivalents to the elements described with reference to the exemplary embodiments disclosed herein may be substituted without departing from the scope of the invention.

Therefore, it is intended that the disclosure not be limited to the particular embodiment(s) disclosed, but that the disclosure will include all embodiments falling within the scope of the appended claims.

Claims (17)

1. A dual refrigerant circuit chiller comprising:

a first refrigerant circuit including a first condenser and a first evaporator;

a second refrigerant circuit including a second condenser and a second evaporator;

a condenser assembly comprising the first condenser and the second condenser interconnected in a continuous cooling fluid circuit, the condenser assembly having a cooling fluid inlet in fluid communication with the second condenser and a cooling fluid outlet in fluid communication with the first condenser; and

an evaporator assembly comprising first and second evaporators interconnected in a continuous fluid circuit and a waterbox disposed intermediate the first and second evaporators, the evaporator assembly having a circuit fluid inlet in fluid communication with the first evaporator and a circuit fluid outlet in fluid communication with the second evaporator, the first evaporator having a multi-pass circuit fluid-to-refrigerant heat exchanger having an outlet in fluid communication with the waterbox and an inlet in fluid communication with the circuit fluid inlet of the evaporator assembly, the second evaporator having a multi-pass circuit fluid-to-refrigerant heat exchanger having an inlet in fluid communication with the waterbox and a circuit fluid outlet in fluid communication with the circuit fluid outlet of the evaporator assembly, the multi-pass circuit fluid-to-refrigerant heat exchanger of the second evaporator having an inlet in fluid communication with the waterbox and a circuit fluid outlet in fluid communication with the evaporator assembly The circuit fluid inlet and the circuit fluid outlet are disposed at opposite longitudinal ends of the evaporator assembly.

2. The dual refrigerant circuit chiller of claim 1 wherein the first evaporator circuit fluid-to-refrigerant heat exchanger and the second evaporator circuit fluid-to-refrigerant heat exchanger each comprise a three pass tube bundle heat exchanger.

3. The dual refrigerant loop chiller as set forth in claim 1, wherein said cooling fluid is cooling water and said loop fluid is chiller water.

4. The dual refrigerant circuit chiller as set forth in claim 1, wherein said condenser assembly comprises: a water tank disposed intermediate the first condenser and the second condenser; a multi-pass cooling fluid to refrigerant heat exchanger in the second condenser having an outlet in fluid communication with the water tank and an inlet in fluid communication with the cooling fluid inlet of the condenser assembly; and a multi-pass cooling fluid to refrigerant heat exchanger in the first condenser having an inlet in fluid communication with the water tank and an outlet in fluid communication with the cooling fluid outlet of the condenser assembly, the cooling fluid inlet and the cooling fluid outlet being disposed at opposite longitudinal ends of the condenser assembly.

5. The dual refrigerant circuit chiller as set forth in claim 1, wherein said evaporator assembly further comprises: a first bypass conduit having an inlet in fluid communication with the circuit fluid inlet of the evaporator assembly and an outlet in fluid communication with a first chamber of the waterbox, wherein a multi-pass circuit fluid-to-refrigerant heat exchanger of the first evaporator has an inlet in fluid communication with the first chamber of the waterbox and an outlet in fluid communication with a second chamber of the waterbox.

6. The dual refrigerant circuit chiller as set forth in claim 5, wherein said evaporator assembly further comprises: a second bypass conduit having an outlet in fluid communication with the circuit fluid outlet of the evaporator assembly and an inlet in fluid communication with the third chamber of the waterbox, wherein the multi-pass circuit fluid-to-refrigerant heat exchanger of the second evaporator has an inlet in fluid communication with the second chamber of the waterbox and an outlet in fluid communication with the third chamber of the waterbox.

7. A dual refrigerant circuit chiller comprising:

a first refrigerant circuit including a first condenser and a first evaporator;

a second refrigerant circuit including a second condenser and a second evaporator;

a condenser assembly comprising a first condenser and a second condenser interconnected in a continuous cooling fluid circuit, the condenser assembly having a cooling fluid inlet in fluid communication with the second condenser and a cooling fluid outlet in fluid communication with the first condenser;

an evaporator assembly comprising a first evaporator and a second evaporator interconnected in a continuous fluid circuit and a water tank disposed intermediate the first evaporator and the second evaporator, the water tank having a first chamber, a second chamber, and a third chamber, the evaporator assembly having:

a circuit fluid inlet and a circuit fluid outlet disposed at opposite longitudinal ends of the evaporator assembly;

a first bypass conduit having an inlet in fluid communication with a circuit fluid inlet of the evaporator assembly and an outlet in fluid communication with the first chamber of the tank;

a first multi-pass circuit fluid-to-refrigerant heat exchanger disposed in the first evaporator, the first multi-pass circuit fluid-to-refrigerant heat exchanger having an inlet in fluid communication with the first chamber of the tank and an outlet in fluid communication with the second chamber of the tank;

a second bypass conduit having an outlet in fluid communication with the loop fluid outlet of the evaporator assembly and an inlet in fluid communication with the third chamber of the waterbox; and

a second multi-pass circuit fluid-to-refrigerant heat exchanger of the second evaporator having an inlet in fluid communication with the second chamber of the waterbox and an outlet in fluid communication with a third chamber of the waterbox.

8. The dual refrigerant circuit chiller of claim 7 wherein the first evaporator circuit fluid-to-refrigerant heat exchanger and the second evaporator circuit fluid-to-refrigerant heat exchanger each comprise a two-pass tube bundle heat exchanger.

9. The dual refrigerant loop chiller as set forth in claim 7, wherein said cooling fluid is cooling water and said loop fluid is water.

10. The dual refrigerant loop cooler of claim 7, wherein the cooling fluid is cooling water and the loop fluid is brine.

11. The dual refrigerant circuit chiller as set forth in claim 7, wherein said condenser assembly comprises: a water tank disposed intermediate the first condenser and the second condenser; a multi-pass cooling fluid to refrigerant heat exchanger in the second condenser having an outlet in fluid communication with the water tank and an inlet in fluid communication with a cooling fluid inlet of the condenser assembly; and a multi-pass cooling fluid to refrigerant heat exchanger in the first condenser having an inlet in fluid communication with the water tank and an outlet in fluid communication with the cooling fluid outlet of the condenser assembly, the cooling fluid inlet and cooling fluid outlet being disposed at opposite longitudinal ends of the condenser assembly.

12. The dual refrigerant loop cooler of claim 7, wherein the cooling fluid is cooling water and the loop fluid is brine.

13. The dual refrigerant circuit chiller as set forth in claim 1, wherein the intermediate tank is divided into a first chamber, a second chamber and a third chamber.

14. The dual refrigerant circuit chiller as set forth in claim 1 wherein said second chamber of said intermediate waterbox provides a generally vertical flow path through said waterbox.

15. The dual refrigerant circuit chiller as set forth in claim 7 wherein said first bypass line extends outside of said evaporator assembly at a first end of said evaporator assembly for connection to a fluid line receiving circuit fluid and said second bypass line extends outside of said evaporator assembly at a second end of said evaporator assembly for connection to a fluid line discharging circuit fluid.

16. The dual refrigerant circuit chiller as set forth in claim 7, wherein said condenser assembly comprises:

the water tank, the water tank is located first condenser with the centre of second condenser, the water tank has first cavity, second cavity and third cavity:

a first bypass duct having an inlet in fluid communication with the cooling fluid inlet of the condenser assembly and an outlet in fluid communication with the first chamber of the water tank;

a first multi-pass cooling fluid to refrigerant heat exchanger disposed in the second condenser, the heat exchanger having an inlet in fluid communication with the first chamber of the water tank and an outlet in fluid communication with the second chamber of the water tank;

a second bypass conduit having an outlet in fluid communication with the loop fluid outlet of the condenser assembly and an inlet in fluid communication with the third chamber of the water tank; and

a second multi-pass cooling fluid to refrigerant heat exchanger disposed in the first condenser, the second multi-pass cooling fluid to refrigerant heat exchanger having an inlet in fluid communication with the second chamber of the water tank and an outlet in fluid communication with a third chamber of the water tank.

17. The dual refrigerant circuit chiller as set forth in claim 16 wherein said first bypass line extends outside of said condenser assembly at a first end of said condenser assembly for receiving cooling fluid and said second bypass line extends outside of said condenser assembly at a second end of said condenser assembly for discharging cooling fluid.