Description:FIELD
The present disclosure relates to waste heat recovery in automobiles. Particularly, the present disclosure relates to utilization of heat recovered from the exhaust gases for cooling of charge air and for operating the HVAC system of the vehicle.
BACKGROUND
The background information herein below relates to the present disclosure but is not necessarily prior art.
The demand of energy for cooling of a truck cabin is conventionally met by means of a vapour compression-based refrigeration system. Most of the developments in technology are focused on vapour compression refrigeration cycle optimization by means of change of working medium and/or development of sub-components, but no significant improvement has been made in the working principle of cooling system to reduce its operational cost.
In trucks with turbocharged engines, intake air for engine, i.e., charge air is compressed by means of a turbocharger driven by exhaust gas of the engine. During the process of compression, charge air gets heated up, resulting in an increase of volume of air and in turn partially takes away the benefit achieved by means of a turbocharged engine. Hence, intercoolers are used to cool charge air to about 50°C in order to decrease its volume and increase the air quantity being charged to engine. The scheme of an intercooler and an HVAC system deployed currently in trucks is shown in Figure 1 and can be observed that a single fan is used to cool the fluids in three heat exchangers namely, a radiator, an intercooler and a condenser.
Conventional intercoolers use ambient air (i.e., direct intercooling) to cool the charge air and hence there is a limitation in cooling the charge air below 50°C. The intercooler efficiency of direct intercoolers is usually in the range of 90%, depending on ambient air conditions. The recent technological solution being assessed for an intercooling system is to configure a liquid (coolant / water) based cooling system (i.e., indirect intercooler). The main driving factors for adapting indirect intercoolers over direct intercoolers are:
• improved BSFC (Brake Specific Fuel Consumption);
• decrease in turbolag;
• improved transient response of the engine; and
• reduction in NOx emission.
The BSFC of the vehicle improves with either reduction of the pressure drop of charge air and/or reduction in charge air temperature. It is possible to reduce both the pressure drop and the temperature of charge air with the liquid-based indirect intercooler system than the currently employed air-based direct intercooler. The range of BSFC improvement potential with indirect intercooling is estimated and includes:
• 10°C lower intake manifold temperature results in 1.9 g/kWh BSFC reduction;
• 10kPa reduction in charge air pressure drop results in 3.5 g/kWh drop in BSFC.
Indirect intercoolers are much compact than the air-based direct intercoolers resulting in reduction of volume of air in the charge air circuit. This reduction in charge air volume results in improvement of engine’s transient behaviour and reduces the response time of turbocharger. Due to the indirect intercooler, the charge air intake loop volume is roughly 50% lower than the direct intercooler and results in improvement of response time. It is observed in studies that indirect intercoolers build up the charge air pressure variation of 5% two times faster when compared to conventional air-based direct intercoolers.
Moreover, in indirect intercoolers, it is observed that there is a delay in increase of charge air outlet temperature during increment of load step due to high thermal inertia of the liquid stream. This results in a significant decrease in temperature peaks of charge air and delays the actuation of radiator fan. The delayed actuation of the radiator fan results in a decrease in the cycle average fan power.
More recently, efforts to sub cool the charge air (~10°C) below ambient temperature have been carried out by coupling the vehicle air conditioning system with the charge air cooling system to obtain advantages on combustion efficiency and to increase the torque of a downsized gasoline engines by 19%.
Due to high ambient temperature in tropical countries, it is impossible to achieve charge air outlet temperature of 25°C or lower than that using either of the direct or indirect intercooler systems. Though one way to achieve sub-cooling of charge air temperature (~10°C) below ambient temperature is possible, the methodology adopted is not highly energy efficient and will not give best fuel savings due to coupling of the vehicle air conditioning system with an intercooler. The additional power required for the air conditioning system to meet intercooler cooling demand will negate the fuel saving benefits significantly.
Moreover, in indirect intercoolers also, a single fan is used to cool the fluids in all the heat exchangers arranged in series, namely, a radiator for engine cooling, a low temperature radiator for intercooling and a condenser for HVAC application, resulting in a high head loss and an increased auxiliary power consumption of the fan.
Hence, there is a need for a charge air cooling system which is highly energy-efficient than the recent developments and an innovative HVAC system for trucks which will have less fuel consumption besides reduction of auxiliary fan power.
In IC engines, it is a known fact that more than 20% of input energy is going as waste heat. Use of exhaust heat has been one of the priorities for many automobile technology developers to improve the efficiency of vehicles. If the exhaust heat can be used for meeting the HVAC and other cooling loads of the automobile space, then the efficiency can be enhanced substantially, and the solution will become a sustainable and green solution that automobile sector is longing for.
OBJECTS
Some of the objects of the present disclosure, which at least one embodiment herein satisfies, are as follows:
A primary object of the present disclosure is to provide a system for waste heat recovery for utilization in charge air cooling system for automobiles, particularly for trucks.
Another object of the present disclosure is to provide an HVAC system for trucks.
Yet another object of the present disclosure is to provide a charge air cooling cum HVAC system for automobiles, which is energy-efficient.
Still another object of the present disclosure is to provide a charge air cooling cum HVAC system for automobiles, which utilizes waste heat energy.
Yet another object of the present disclosure is to provide a charge air cooling cum HVAC system for automobiles, which provides for removal of liquids accumulated within the box.
Other objects and advantages of the present disclosure will be more apparent from the following description, which is not intended to limit the scope of the present disclosure.
SUMMARY
The present disclosure envisages a waste heat recovery system for an automobile. The waste heat recovery system is configured to provide cooling of charge air by operating on waste heat energy recovered from exhaust gases of the automobile. The system comprises a high temperature liquid circuit, heat recovery unit, an intercooler, a catalyst bed, a low temperature liquid circuit, a medium temperature liquid circuit and a radiator-and-fan arrangement.
The high temperature liquid circuit circulates a heat transferring fluid. The heat recovery unit is configured as a heat exchanger for absorbing heat energy from a stream of exhaust gas generated by the engine of the automobile, for receiving the heat transferring fluid of the high temperature liquid circuit and for passing the absorbed heat energy to the heat transferring fluid flowing through the high temperature liquid circuit. The heat transferring fluid flowing through the high temperature circuit is also referred to as high temperature fluid in the present description.
The intercooler is configured as a heat exchanger for cooling at least one of charge air and cabin air.
The catalyst bed is configured to adsorb the high temperature fluid and to release heat of adsorption from the high temperature fluid while also absorbing heat from a low temperature fluid.
The low temperature liquid circuit of the low temperature fluid is configured to pass through the intercooler and the catalyst bed. The low temperature fluid is configured to absorb heat from the charge air or the cabin air in the intercooler.
The medium temperature liquid circuit is configured to pass through catalyst bed and to withdraw the heat released by the catalyst bed. The radiator-and-fan arrangement is configured to dissipate heat absorbed by the medium temperature liquid circuit.
Preferably, a mixture of ethylene glycol and water with pre-defined amount is used as the heat transferring fluid. When the range of temperature of operation of the heat transferring fluid is from 120°C to 135°C, it is referred as high temperature fluid.
When the range of temperature of operation of the heat transferring fluid is from 40°C to 60°C, it is referred as medium temperature fluid.
When the range of temperature of operation of the heat transferring fluid is from 5°C to 10°C, it is referred as low temperature fluid.
In an embodiment, the intercooler is configured to receive compressed charge air from a turbocharger.
In a preferred embodiment, the range of supply temperature of the charge air and the cabin air is from 10°C to 25°C.
Typically, the radiator-and-fan arrangement includes a low temperature radiator through which the medium temperature liquid circuit passes and a second fan for blowing air over the low temperature radiator.
In an embodiment, the heat recovery unit is mounted coaxial to the exhaust gas pipe at the rear lower end of the underbody of the automobile. Preferably, the heat recovery unit is positioned behind a rear wheel under either left or right peripheral area of the underbody of the automobile.
In an embodiment, the catalyst bed is mounted at a central position below the underbody of the automobile.
In an embodiment, the piping of the low temperature liquid circuit is located on top of the cabin of the automobile.
In an embodiment, the low temperature radiator and the second fan are mounted on top of the cabin, and in an exposed state to receive the draft of air as the vehicle moves forward.
BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWING
A waste heat recovery system for an automobile, of the present disclosure, will now be described with the help of the accompanying drawing, in which:
Figure 1 illustrates a thermal management and HVAC system of prior art;
Figure 2 illustrates a waste heat recovery system of the present disclosure;
Figure 3 illustrates a schematic view of a truck showing installation of various components of the waste heat recovery system of Figure 2.
LIST OF REFERENCE NUMERALS
5 Engine
10 Exhaust gas stream
121 DOC - Diesel Oxidation Catalyst
122 DPF - Diesel Particulate Filter
123 SCR - Selective Catalytic Reducer
124 ASC - Ammonia Slip Catalyst
141 Turbine
142 First Compressor
16 Engine coolant circuit
161 High temperature radiator
162 First fan
18 Intercooler
20’ Cabin HVAC system of prior art
201’ Condenser
202’ Second compressor
30 Charge air
40 High temperature liquid circuit
42 Heat recovery unit
44 Catalyst bed
50 Medium temperature liquid circuit
51 Low temperature radiator
52 Second fan
60 Low temperature liquid circuit
62 Cabin air
70 Truck
72 Cabin
74 Engine compartment
76 Underbody
78a Front wheel
78b Rear wheel
DETAILED DESCRIPTION
Embodiments, of the present disclosure, will now be described with reference to the accompanying drawing.
Embodiments are provided so as to thoroughly and fully convey the scope of the present disclosure to the person skilled in the art. Numerous details are set forth, relating to specific components, and methods, to provide a complete understanding of embodiments of the present disclosure. It will be apparent to the person skilled in the art that the details provided in the embodiments should not be construed to limit the scope of the present disclosure. In some embodiments, well-known processes, well-known apparatus structures, and well-known techniques are not described in detail.
The terminology used, in the present disclosure, is only for the purpose of explaining a particular embodiment and such terminology shall not be considered to limit the scope of the present disclosure. As used in the present disclosure, the forms “a”, “an” and “the” may be intended to include the plural forms as well, unless the context clearly suggests otherwise. The terms “comprises”, “comprising”, “including” and “having” are open ended transitional phrases and therefore specify the presence of stated features, elements, modules, units and/or components, but do not forbid the presence or addition of one or more other features, elements, components, and/or groups thereof.
The terms first, second, third, etc., should not be construed to limit the scope of the present disclosure as the aforementioned terms may be only used to distinguish one element, component or section from another component or section. Terms such as first, second, third etc., when used herein do not imply a specific sequence or order unless clearly suggested by the present disclosure.
A typical cabin air cooling arrangement using an intercooler is shown in the schematic diagram of Figure 1. The intercooler 18 shown therein uses ambient air to cool the charge air 30. Thus, in tropical countries with very high summer temperatures, for intercoolers in outdoor vehicles like trucks, there is a limitation in cooling the charge air below 50°C. Hence, an indirect coolant-based intercooling for charge air is sought for improving the overall energy efficiency of the system.
Figure 2 shows a schematic diagram of a waste heat recovery system for an automobile. The waste heat recovery system is configured to provide cooling of charge air by operating on waste heat energy recovered from exhaust gases of the automobile. The waste heat recovery system comprises a high temperature liquid circuit 40 in cooperation with a heat recovery unit 42 and a catalyst bed 44. The heat recovery unit 42 is configured as a heat exchanger for absorbing heat energy from a stream of exhaust gas 10 generated by the engine 5 of the automobile, for receiving the refrigerant of the high temperature liquid circuit 40 and passing the absorbed heat energy to the refrigerant flowing through the high temperature liquid circuit 40. The catalyst bed 44 is configured to adsorb the refrigerant and release heat of adsorption from the refrigerant while also absorbing heat from a low temperature fluid. An intercooler 18 is configured as a heat exchanger for cooling at least one of charge air 30 and cabin air 62. A low temperature liquid circuit 60 of the low temperature fluid is configured to pass through the intercooler 18 and the catalyst bed. The low temperature fluid is configured to absorb heat from the charge air 30 or the cabin air 62 in the intercooler 18. A medium temperature liquid circuit 50 is configured to pass through catalyst bed 44 for withdrawing the heat released by the catalyst bed 44. A radiator-and-fan arrangement 51-52 is configured to dissipate heat absorbed by the medium temperature liquid circuit 50. Thus, the utilization of heat energy of the exhaust gases for cooling of charge air 30 and/or cabin air 62 is based on the principle of sorption cooling.
Preferably, a mixture of ethylene glycol and water with pre-defined amount is used as the high temperature fluid. The range of temperature of operation of the refrigerant is from 120°C to 135°C.
Preferably, a mixture of ethylene glycol and water with pre-defined amount is used as the medium temperature fluid. The range of temperature of operation of the medium temperature fluid is from 40°C to 60°C.
Preferably, a mixture of ethylene glycol and water with pre-defined amount is used as the medium temperature fluid. The range of temperature of operation of the medium temperature fluid is from 5°C to 10°C.
The charge air 30 is typically sucked in at atmospheric conditions, i.e., 35-40°C in a compressed state through a turbocharger 141-142 into the intercooler 18. The turbine 142 of the turbocharger is operated by pressure of exhaust gases exiting the engine 5. The intercooler 18 receives cool low temperature fluid at around 5-10°C, which absorbs heat from the charge air 30. At the same time, cabin air 62 of the truck also circulates through the intercooler 18 and gets cooled. The temperature of charge air supplied to the engine 5 is in the range of 25°C-10°C. Similar temperatures can be achieved for the cabin air 62. The low temperature fluid discharges heat to the catalyst bed 44. The catalyst bed 44 adsorbs the heated refrigerant and discharges heat of adsorption to the medium temperature liquid circuit at 40-60°C. The medium temperature fluid discharges the absorbed heat at the radiator-fan arrangement 51-52 which comprises the low temperature radiator 51 and the second fan 52. The refrigerant gets heated to 120-135°C at the heat recovery unit 42 due to the hot exhaust gases arriving from the engine 5.
The exhaust gases of the diesel engine 5 may be treated at a DOC 121 (diesel oxidation catalyst), a DPF 122 (diesel particulate filter), a SCR 123 (selective catalytic reducer) and an ASC 124 (ammonia slip catalyst), preferably in that order, before entering the heat recovery unit 42.
A conventional high temperature radiator-fan arrangement 161-162 is provided for cooling the engine 5 using a coolant circulating at around 80°C.
In a typical layout of a truck 70, as illustrated in Figure 3, the high temperature radiator 161 along with the corresponding first fan 162 is positioned in front of the vehicle body, particularly in front of the engine compartment 74. The heat recovery unit 42 is mounted coaxial to the exhaust gas pipe (not shown in Figures) at the rear lower end of the vehicle underbody 76. Specifically, the heat recovery unit 42 is positioned behind a rear wheel 78b under either left or right peripheral area of the vehicle body, depending upon lateral position of the exhaust gas pipe. The catalyst bed 44 is mounted at a central position below the underbody 76. The piping of the low temperature liquid circuit 60 is located on top of the cabin 72. The low temperature radiator 51 and the second fan 52 are also mounted on top of the cabin 72, and in an exposed state so as to receive the draft of air as the truck 70 moves forward. However, the heat recovery unit 42, the catalyst bed 44, the low temperature liquid circuit 60, the low temperature radiator 51 and the second fan 52 can be positioned elsewhere based on space availability, truck manufacturer’s packaging requirements and system optimization.
The charge air will be cooled to around 25°C and as low as 10°C based on engine’s efficient operation requirements and availability of waste heat generated by the engine. The expected fuel savings resulted due to decrease in charge air temperature, charge air pressure drop in intercooler and auxiliary power consumption reduction of radiator fan, compressor of VC refrigeration system is more than 8% at normal operation conditions. The fuel savings will vary depending on operating conditions and ambient conditions.
The foregoing description of the embodiments has been provided for purposes of illustration and not intended to limit the scope of the present disclosure. Individual components of a particular embodiment are generally not limited to that particular embodiment, but, are interchangeable. Such variations are not to be regarded as a departure from the present disclosure, and all such modifications are considered to be within the scope of the present disclosure.
TECHNICAL ADVANCEMENTS
The present disclosure described herein above has several technical advantages including, but not limited to, the realization of a waste heat recovery system, that:
• enhances fuel efficiency while providing for charge air cooling and cabin cooling;
• eliminates the need of a condenser for cooling;
• bifurcates power required for radiator-fan arrangement and thus helps in further energy optimization;
• provides high face area due to positioning of the T-HVAC radiator above roof top, resulting in reduced fan power and uniform air distribution;
• increases power output of the engine by more than 15% as compared to vehicles employing direct intercooling for charge air;
• reduces NOx and CO2 emissions;
• reduces turbolag; and
• improves transient response of the engine.
The embodiments herein and the various features and advantageous details thereof are explained with reference to the non-limiting embodiments in the following description. Descriptions of well-known components and processing techniques are omitted so as to not unnecessarily obscure the embodiments herein.
The foregoing description of the specific embodiments so fully reveal the general nature of the embodiments herein that others can, by applying current knowledge, readily modify and/or adapt for various applications such specific embodiments without departing from the generic concept, and, therefore, such adaptations and modifications should and are intended to be comprehended within the meaning and range of equivalents of the disclosed embodiments. It is to be understood that the phraseology or terminology employed herein is for the purpose of description and not of limitation. Therefore, while the embodiments herein have been described in terms of preferred embodiments, those skilled in the art will recognize that the embodiments herein can be practiced with modification within the spirit and scope of the embodiments as described herein.
The use of the expression “at least” or “at least one” suggests the use of one or more elements or ingredients or quantities, as the use may be in the embodiment of the disclosure to achieve one or more of the desired objects or results.
While considerable emphasis has been placed herein on the components and component parts of the preferred embodiments, it will be appreciated that many embodiments can be made and that many changes can be made in the preferred embodiments without departing from the principles of the disclosure. These and other changes in the preferred embodiment as well as other embodiments of the disclosure will be apparent to those skilled in the art from the disclosure herein, whereby it is to be distinctly understood that the foregoing descriptive matter is to be interpreted merely as illustrative of the disclosure and not as a limitation
, Claims:WE CLAIM:
1. A waste heat recovery system for an automobile, said waste heat recovery system configured to provide cooling of charge air by operating on waste heat energy recovered from exhaust gases of the automobile, said system comprising:
i. a high temperature liquid circuit (40) configured to circulate a high temperature fluid;
ii. a heat recovery unit (42) configured as a heat exchanger for absorbing heat energy from a stream of exhaust gas generated by the engine (5) of the automobile, for receiving said high temperature fluid of said high temperature liquid circuit (40) and for passing the absorbed heat energy to said high temperature fluid flowing through said high temperature liquid circuit (40);
iii. an intercooler (18) configured as a heat exchanger for cooling at least one of charge air (30) and cabin air (62);
iv. a catalyst bed (44) configured to adsorb said refrigerant and release heat of adsorption from said refrigerant while also absorbing heat from a low temperature fluid;
v. a low temperature liquid circuit (60) of said low temperature fluid configured to pass through said intercooler (18) and said catalyst bed (44), said low temperature fluid configured to absorb heat from the charge air (30) or the cabin air (62) in said intercooler (18);
vi. a medium temperature liquid circuit (50) of a medium temperature fluid configured to pass through catalyst bed (44) and withdraw the heat released by said catalyst bed (44); and
vii. a radiator-and-fan arrangement (51-52) configured to dissipate heat absorbed by said medium temperature liquid circuit (50).
2. The waste heat recovery system as claimed in claim 1, wherein said high temperature fluid is a mixture of pre-defined amounts of ethylene glycol and water.
3. The waste heat recovery system as claimed in claim 2, wherein the range of temperature of operation of said high temperature fluid is from 120°C to 135°C.
4. The waste heat recovery system as claimed in claim 1, wherein said medium temperature fluid is a mixture of pre-defined amounts of ethylene glycol and water.
5. The waste heat recovery system as claimed in claim 4, wherein the range of temperature of operation of said medium temperature fluid is from 40°C to 60°C.
6. The waste heat recovery system as claimed in claim 1, wherein said low temperature fluid is a mixture of pre-defined amounts of ethylene glycol and water.
7. The waste heat recovery system as claimed in claim 6, wherein the range of temperature of operation of said low temperature fluid is from 5°C to 10°C.
8. The waste heat recovery system as claimed in claim 1, wherein said intercooler (18) is configured to receive compressed charge air from a turbocharger (141-142).
9. The waste heat recovery system as claimed in claim 1, wherein the range of supply temperature of said charge air (30) and said cabin air (62) is from 10°C to 25°C.
10. The waste heat recovery system as claimed in claim 1, wherein said radiator-and-fan arrangement includes a low temperature radiator (51) through which said medium temperature liquid circuit (50) passes and a second fan (52) for blowing air over said low temperature radiator (51).
11. The waste heat recovery system as claimed in claim 1, wherein said heat recovery unit is mounted coaxial to the exhaust gas pipe at the rear lower end of the underbody (76) of the automobile.
12. The waste heat recovery system as claimed in claim 11, wherein said heat recovery unit (42) is positioned behind a rear wheel under either left or right peripheral area of the underbody (76) of the automobile.
13. The waste heat recovery system as claimed in claim 1, wherein said catalyst bed (44) is mounted at a central position below the underbody (76).
14. The waste heat recovery system as claimed in claim 1, wherein the piping of the low temperature liquid circuit (60) is located on top of the cabin (72).
15. The waste heat recovery system as claimed in claim 1, wherein said low temperature radiator (51) and said second fan (52) are mounted on top of the cabin (72), and in an exposed state to receive the draft of air as the automobile moves forward.
Dated this 03rd day of January, 2023

_______________________________
MOHAN RAJKUMAR DEWAN, IN/PA – 25
of R.K.DEWAN & CO.
Authorized Agent of Applicant

TO,
THE CONTROLLER OF PATENTS
THE PATENT OFFICE, AT MUMBAI