PROVIDING ENGINE HEAT TO AN ABSORPTION CHILLER

1. Technical Field

[0001] This disclosure relates to absorption chillers. More particularly, this disclosure relates to providing heat to an absorption chiller.

2. Description of Related Art

[0002] Absorption chillers are well-known. The typical absorption chiller evaporates fluid, such as ammonia, to remove heat from a surrounding environment. The absorption chiller may include a boiler section, a condenser section, an evaporator section, and an absorption section. Although many substances may be used within the absorption chiller, typical absorption chillers include ammonia, lithium bromide, and water. Providing heat to the absorption chiller allows for evaporating fluid to drive an absorption chiller cooling cycle.

[0003] An absorption chiller can be used as part of an energy efficient system in either a cogeneration configuration (electric power and air conditioning) or in a tri-generation configuration (electric power, heat and air conditioning). On- site power generation applications are becoming increasingly common, for purposes of either distributed power generation or back-up power generation. In either case, the prime mover for the electric generator may be an internal combustion engine. These engines produce heat as a by-product. Typically this heat comes from two sources within the engine: from a water jacket surrounding the combustion chambers and from the process exhaust stream. This heat is useful for other purposes on the site, such as for process or space heating, or for air conditioning. An absorption chiller can use this waste heat produced by an internal combustion engine to drive a cooling cycle and provide air conditioning.

[0004] Increasing the temperature of the heat available to the absorption chiller will increase the cooling effectiveness of the chiller. Existing absorption chiller arrangements utilize multiple heat exchangers and fluid loops to use heat from the

engine for operating the absorption chiller. Each transfer or exchange of heat results in some degradation of temperature from the heat source.

[0005] The schematic of Figure 1 shows a prior art arrangement 10 for using heat from an engine 12 for providing heat to an absorption chiller 14. As is known, the engine 12 generates heat as it powers a generator 18. The engine 12 commonly includes an exhaust portion 22 and a water jacket portion 26. Heated exhaust flows away from the exhaust portion 22 of the engine 12, along a line 30, and through a heat exchanger 38 before it enters the environment at 48. The water jacket 26 is used for cooling the engine 12. Heated fluid from the water jacket 26 flows along a line 34 and through a heat exchanger 42 before it returns to the water jacket 26.

[0006] The absorption chiller 14 includes a fluid line 46 in communication with the heat exchanger 38 and the heat exchanger 42. Heat from the fluids leaving the engine 12 is absorbed by the fluid in the line 46 in the heat exchangers 38 and 42. The prior art arrangement 10 uses three lines 30, 46, and 34 and the two heat exchangers 38 and 42 to communicate heat. The prior art arrangement 10 includes inefficiencies because the temperature of the fluids at the water jacket portion 26 and the exhaust portion 22 drops before the heat transfer at the heat exchanger 38 and the heat exchanger 42. A difference of even a few degrees in the temperature of the fluid provided to the chiller can significantly reduce the performance. For example, a 200° F temperature provides adequate heat but at 190° F chiller performance decreases significantly.

[0007] It would be desirable to provide an improved absorption chiller heating arrangement.

SUMMARY [0008] An example method of providing heat to an absorption chiller includes communicating a fluid from the absorption chiller to an engine, heating the fluid at the location of the engine, and communicating the heated fluid to the absorption chiller.

[0009] One example includes heating the fluid using heat from a water jacket of the engine and circulating the fluid between the absorption chiller and the engine.

[0010] An example arrangement for providing heat to an absorption chiller includes an absorption chiller, and a fluid path for circulating fluid between the absorption chiller and the engine where the fluid is heated. The fluid path then communicates the heated fluid to the absorption chiller. The fluid carries heat from the engine directly to the absorption chiller.

[0011] The various features and advantages of this disclosure will become apparent to those skilled in the art from the following detailed description. The accompanying drawings can be briefly described as follows.

BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1 schematically shows a prior art absorption chiller arrangement. [0013] Figure 2 schematically shows an example arrangement designed according to an embodiment of this disclosure for providing heat generated by an engine to an absorption chiller.

[0014] Figure 3 schematically shows another example arrangement designed according to an embodiment of this disclosure for providing heat generated by an engine to an absorption chiller.

[0015] Figure 4 schematically shows another example arrangement designed according to an embodiment of this disclosure for providing heat generated by an engine to an absorption chiller.

DETAILED DESCRIPTION

[0016] An example arrangement 50 is shown schematically in Figure 2. An engine 52 provides heat to an absorption chiller 54. The engine 52, which is a reciprocating engine in one example, drives an electrical generator 58. The engine 52

includes an exhaust portion 62 and a water jacket portion 66. The illustrated arrangement 50 includes a heat exchanger 78 for transferring heat from the engine 52.

[0017] The absorption chiller 54 requires heat to drive a cooling cycle. In this example, fluid flows through a line 74 directly from the absorption chiller 54 to the engine 52 and back to the absorption chiller 54. The fluid absorbs heat from the engine 52 and carries the heat back to the absorption chiller 54. Line 74 provides the path of the fluid, a chiller working fluid, flowing directly between the absorption chiller 54 and the engine 52 that does not require a heat exchanger away from the engine as was used in the prior art. A pump (not illustrated) may be used to achieve a desired flow. [0018] The water jacket portion 66 helps to transfer heat from the engine 52 to the fluid flowing within the line 74. In one example, the fluid in the water jacket portion 66 is the fluid from line 74. In such an example, the fluid flowing along the line 74 also circulates through the water jacket portion 66 to remove heat from the engine 52. Alternatively, the water jacket portion 66 includes a second fluid, such as water, for transferring heat from the engine 52 to the fluid flowing in line 74. The second fluid is separate from the chiller working fluid that flows along line 74. Heat moves from the second fluid to the fluid flowing within line 74. Fluids within the water jacket portion 66 may reach temperatures ranging from 180-200° F.

[0019] After absorbing heat from the engine 52, heated fluid returns to the absorption chiller 54 along line 74. The heat within the fluid drives the cooling cycle of the absorption chiller 54. Moving the fluid directly between the engine 52 and the absorption chiller 54 provides higher quality heat (i.e. heat at a higher temperature) compared to previous designs. In one example, water flowing between the absorption chiller 54 and the engine 52 increases the temperature of the water returning to the absorption chiller 54 by about 4 degrees over the prior art arrangements and provides about 1 RT more chilling capacity for the same amount of input heat.

[0020] In the illustrated example, exhaust from the engine 52 provides another source of heat for the absorption chiller 54. As fluid in the line 74 moves through a heat exchanger 78, it absorbs additional heat from the exhaust. A line 70 carries hot exhaust from the exhaust portion 62 of the engine 52, through the heat

exchanger 78 before it is released to the environment at 76. Various types of heat exchangers 78 may be used, such as a shell-and-tube type heat exchanger.

[0021] Fluid, such as water or oil for example, flowing along the line 74 moves directly from the absorption chiller 54 into a portion of the engine 52. The fluid absorbs heat within the engine 52 and flows back to the absorption chiller 54. The fluid may move through the heat exchanger 78 to absorb additional heat. Directly routing the fluid between the engine 52 and the absorption chiller 54 results in a higher heat source temperature to the chiller.

[0022] In the example of Figure 3, the fluid flowing along line 74 absorbs heat from a first heat transfer portion at the location of the engine 52 and a second heat transfer portion at the location of the engine 52. The second heat transfer portion is proximate the engine exhaust 70 and is fluidly coupled to the absorption chiller 54. Fluid flowing along line 74 absorbs heat from the water jacket 66 and the exhaust 62 portions of the engine 52. [0023] The example of Figure 4 functions much like the example of Figure 3 with the addition of the heat exchanger 78 separate from the engine 52. The fluid absorbs heat from the first and second heat transfer portions at the location of the engine 52. The fluid then absorbs addition heat from the engine exhaust 70 at the heat exchanger 78. [0024] The preceding description is exemplary rather than limiting in nature.

Variations and modifications to the disclosed examples may become apparent to those skilled in the art that do not necessarily depart from the essence of this disclosure. The scope of legal protection given to this disclosure can only be determined by studying the following claims.