Patent Application
20130019819
The present disclosure relates to a coolant circuit for an engine, and more particularly to a coolant circuit using a bypass line.
A coolant circuit for an engine may include a bypass line along with a heat exchanger. Based on the cooling load of the engine, the bypass line short-circuits a flow of the coolant through the heat exchanger when the demand on the coolant circuit for cooling the engine is low. U.S. Pat. No. 5,642,691 uses such a bypass line for short-circuiting the flow of the coolant through the heat exchanger.
In one aspect, the present disclosure provides a coolant circuit for cooling of an engine. The coolant circuit includes an inlet line configured to receive a coolant from the engine. The coolant circuit further includes a heat exchanger connected to the inlet line for receiving the coolant. The heat exchanger is configured to remove heat from the coolant. An outlet line is provided in the coolant circuit to receive the coolant from the heat exchanger. The coolant circuit further includes a bypass line disposed between the inlet line and the outlet line. The coolant circuit also includes a control valve, such that the control valve allows the flow of the coolant through the bypass line and the heat exchanger, when the control valve is in a fully open position.
In another aspect, the present disclosure provides a method for cooling the engine. The method includes receiving the coolant from the engine into the inlet supply line, in fluid communication with the heat exchanger. The method further includes regulating flow of the coolant through the heat exchanger, in conjunction with the bypass line. The coolant passes through the heat exchanger and the bypass line when the control valve is in the fully open position. The method further includes passing the coolant from the heat exchanger and the bypass line to the outlet line and finally sending the coolant from the outlet line to the engine.
Other features and aspects of present disclosure will be apparent from the following description and the accompanying drawings.
A power system 1 in which disclosed embodiments may be implemented is schematically illustrated in
The power system 1 further includes a cooling system 100 to cool the engine 10. The cooling system 100 may include a coolant circuit 200, a sea-water circuit 300, and a separate circuit 400. The coolant circuit 200, the sea-water circuit 300, and the separate circuit 400 may work in conjunction to cool the engine 10. The cooling system 100 may utilize power from the engine 10 for operation.
The coolant circuit 200 may be a closed-loop circuit associated with the engine 10. The coolant circuit 200 may include a supply line 202, a delivery line 204, and a heat exchanger 210. The supply line 202 and the delivery line 204 may allow a coolant to circulate in the coolant circuit 200. The coolant used in the coolant circuit 200 may include a mixture of water, antifreeze agent, and rust inhibiter. However, in various other embodiments, the coolant may include, for example, propylene glycol or ethylene glycol.
The heat exchanger 210 is connected to the supply line 202 through an inlet line 206. The inlet line 206 supplies the coolant to the heat exchanger 210 from the supply line 202. Further, the heat exchanger 210 may be connected to the delivery line 204 through an outlet line 208 to supply the coolant back to the engine 10. In an embodiment, the heat exchanger 210 may be located in close proximity to the engine 10. The heat exchanger 210 may be formed integrally with the engine 10.
The coolant circuit 200 further includes a coolant pump 220 provided in the delivery line 204. Alternatively, the coolant pump 220 may be disposed on the supply line 202. Based on a cooling load of the engine 10, a plurality of coolant pumps may be employed. The coolant pump 220 creates a pressure head to circulate the coolant in the coolant circuit 200. In an embodiment, the coolant pump 220 may be a centrifugal pump having a construction well known in the art.
The coolant circuit 200 may further include a control valve 230 disposed on either the inlet line 206 or the outlet line 208. In an embodiment of the present disclosure, the control valve 230 is disposed on the outlet line 208. The control valve 230 may be a three-way thermostatic valve. In an embodiment, the control valve 230 may be configured to be in either one of the two operating state, a fully open position or a closed position to control the flow of the coolant in the coolant circuit 200.
In an embodiment, the coolant circuit 200 includes a bypass line 240. The bypass line 240 is disposed between the inlet line 206 and the outlet line 208, fluidically coupling the inlet line 206 to the outlet line 208. Therefore, the bypass line 240 may provide an additional path for the flow of the coolant, in conjunction with the flow of the coolant through the heat exchanger 210. In an embodiment, the bypass line 240 may be a permanent tube defining an uninterrupted passage for the flow of the coolant when the control valve 230 is in the fully open position. In an embodiment, the bypass line 240 may be disposed in a parallel configuration with the heat exchanger 210. In another embodiment, the bypass line 240 may be integrated into the heat exchanger 210 or be any other type of passage fluidically coupling the inlet line 206 to the outlet line 208.
In an embodiment, the coolant circuit 200 may further include a service line 250, in addition to the bypass line 240. The service line 250 may also be disposed between the inlet line 206 and the outlet line 208. The service line 250 may provide an alternate path for the flow of the coolant when the control valve 230 is in the closed position. The service line 250 may short-circuit the flow of the coolant through the heat exchanger 210 as well as the bypass line 240.
The coolant circuit 200 may further include turbo unit 260 disposed in either the supply line 202 or the delivery line 204. The turbo unit 260 may increase the pressure of the coolant by using exhaust gases from the engine 10. Moreover, the engine 10 may be associated with an engine oil-cooler 270 to cool engine oil which is further used to carry heat away from the engine 10. The engine oil-cooler 270 may be coupled to the coolant circuit 200 to cool the engine oil. The coolant circuit 200 may also include an after-cooler 280. The after-cooler 280 may cool compressed air prior to be sent to the engine 10.
As illustrated in
In an embodiment, the separate circuit 400 may include a separate circuit pump 402 to circulate a cooling fluid. The separate circuit 400 may also include a separate circuit after-cooler 404 and an auxiliary heat exchanger 406. The auxiliary heat exchanger 406 may receive the sea-water from the sea-water line 304 to cool the cooling fluid. The separate circuit 400 may also include a valve 408 to control the flow of the cooling fluid.
The thermostat 234 responds to the temperature of the coolant flowing through the housing 232 in the control valve 230. In an embodiment, the control valve 230 includes a sealed wax pallet to control the movement of the thermostat 234 based on the temperature of the coolant. As illustrated in
As illustrated in the embodiment of
As illustrated in
To meet the cooling requirement of the engine 10, the coolant circuit 200 of the present disclosure may employ a plate-type heat exchanger 210. In the heat exchanger 210, the heat exchanging elements 214 may be of plate-type configuration to provide a large surface area for effective cooling of the coolant. However, the plate-type heat exchanger 210 may also lead to high pressure drop in the coolant. The high pressure drop in the coolant may increase power consumption of the coolant pump 220 in the coolant circuit 200 which adds to an overall operating cost of the power system 1.
To minimize the pressure drop and still achieve considerably the same performance of the heat exchanger 210, the bypass line 240 is introduced in the coolant circuit 200. The bypass line 240 may allow for a larger heat exchanger 210 to be used which minimizes the pressure drop. The pressure drop across the heat exchanger 210 may create a pressure difference such that a portion of the coolant may pass through the bypass line 240. It may be understood that, the higher the pressure drop across the heat exchanger 210 the more the coolant flows through the bypass line 240.
Further, the coolant from the heat exchanger 210 at low pressure (due to pressure drop) and the coolant from the bypass line 240 at relatively high pressure may mix in the outlet line 208. This leads to an increase in the pressure of the coolant in the outlet line 208, and thus reduces the pressure head to be provided by the coolant pump 220 in the coolant circuit 200 which reduces the operating cost of the power system 1.
In the coolant circuit 200, the size of the bypass line 240 may vary depending on various parameters like the size of the heat exchanger 210, configuration of the heat exchanger 210, the engine cooling load, etc. The increase in the size of the bypass line 240 may result in lower pressure drop in the coolant and consequently reduced pressure head to be provided by the coolant pump 220. However, the size of the bypass line 240 may be selected to optimize the required pressure head and cooling performance in the heat exchanger 210. In an embodiment, the bypass line 240 may have a tubular structure having a diameter in a range of about 0.5 inches to 1.5 inches.
As illustrated in process flow 500 of
Further in step 504, the flow of the coolant in the coolant circuit 200 is regulated by the control valve 230. The control valve 230 may switch to the fully open position or the closed position based on the temperature of the coolant. When the temperature of the coolant is above a threshold temperature, as described above, the thermostats may switch the control valve 230 to the fully open position. In the fully open position, the coolant flows through the heat exchanger 210 and the bypass line 240. When the temperature of the coolant is below the threshold temperature, the control valve 230 may switch to the closed position causing the coolant to flow through the service line 250.
Subsequently in step 506, the coolant from the heat exchanger 210 may be discharged into the outlet line 208. The coolant from the heat exchanger 210 may mix with the coolant from the bypass line 240. Further, the coolant from the heat exchanger 210 and the bypass line 240 is sent to the outlet line 208.
Finally in step 508, the coolant from the outlet line 208 is sent to the engine 10 via the delivery line 204. The coolant may flow to the engine 10 by the pressure head created by the coolant pump 220 in the coolant circuit 200. In an embodiment, the coolant may be received in the engine 10 by an engine jacket (not illustrated) enveloping the cylinder block 12. The coolant may flow in the engine jacket which extracts heat from the cylinder block 12 and thus cools the engine 10.
It will be apparent to those skilled in the art that various modification and variations can be made to the disclosed cooling system 100 and more particularly to the coolant circuit 200. Other embodiments will be apparent to those skilled in the art from consideration of the specification and practice of the disclosed system and method. It is intended that the specification and examples be considered as exemplary only, with a true scope being indicated by the following claims and their equivalents.
