Engine waste heat recovery nanometer mixed working medium, system and method thereof

Abstract

The present application relates to the technical field of engine, in particular to a kind of engine waste heat recovery nanometer mixed working medium and its system and method, engine waste heat recovery system includes working medium pump, regenerator, evaporator, turbine, condenser and throttle valve;The present application uses nanometer mixed working medium as the working medium of organic rankine cycle, uses the mixed mode of organic working medium 1,1,1,2-tetrafluoroethane and metal organic framework material Cr-MIL-101 or Mg-MOF-74, relative to other mixed working medium, can improve the heat absorption of circulating working medium, effectively improve the system performance of organic rankine cycle;Through regenerator, the heat of the outflow working medium in turbine can be effectively utilized, the temperature of working medium entering evaporator is improved, working medium continues to heat up after coming out of regenerator, becomes saturated steam or superheated steam, through the combined heat transfer of evaporator and regenerator, the flow of nanometer mixed working medium can be increased, the output shaft power is improved, and the system performance is improved.

Description

Technical Field

[0001] This invention relates to the field of engine technology, and in particular to a nano-mixed working fluid for engine waste heat recovery, and its system and method. Background Technology

[0002] With the continuous increase in the number of cars and the increasing energy crisis, the recovery and utilization of waste heat from vehicle engines is an effective way to improve engine thermal efficiency, reduce pollutant emissions and save energy. In addition, for all-terrain vehicles, due to the compact layout of light all-terrain vehicles, simply relying on air cooling or water cooling to recover engine waste heat can no longer meet the cooling requirements of the entire vehicle, thus affecting the normal operation of the vehicle and even shortening the service life of heat source components.

[0003] Currently, the method used to recover waste heat from vehicle engines is usually the organic Rankine cycle system. Most organic Rankine cycle systems use pure organic working fluid. However, due to the pinch point temperature difference, the temperature matching effect between the pure organic working fluid and the heat source is poor, which greatly limits the improvement of the cycle efficiency and net work of the organic Rankine cycle system. Summary of the Invention

[0004] The purpose of this invention is to provide a nano-mixed working fluid for engine waste heat recovery, and a system and method thereof. Metal-organic framework material nanoparticles are added to an organic working fluid to form a metal-organic heat carrier nano-mixed working fluid. By utilizing the mutual conversion of thermal energy and surface energy during the adsorption and separation of organic working fluid molecules on the solid surface of the metal-organic framework material, the mechanism of action of the working fluid in the organic Rankine cycle system components is changed, thereby improving the performance of the organic Rankine cycle system.

[0005] To achieve the above objectives, in a first aspect, the present invention provides an engine waste heat recovery system, comprising a working fluid pump, a regenerator, an evaporator, a turbine, a condenser, and a throttle valve;

[0006] The regenerator is connected to the working fluid pump and is located on the side of the working fluid pump; the evaporator is connected to the regenerator and is located on the side of the evaporator; the turbine is connected to both the evaporator and the regenerator and is located between the evaporator and the regenerator; the condenser is connected to both the regenerator and the working fluid pump and is located between the regenerator and the working fluid pump; the throttling valve is connected to both the evaporator and the condenser and is located between the evaporator and the condenser.

[0007] Secondly, the present invention also provides a method for recovering waste heat from an engine, comprising:

[0008] The nano-mixed working fluid is pressurized and enters the regenerator via a working fluid pump;

[0009] The nano-mixed working medium absorbs heat from the turbine outlet nano-mixed working medium in the regenerator, and then flows into the evaporator;

[0010] The nano-mixed working medium absorbs heat released by the engine in the evaporator to become high-temperature and high-pressure saturated steam or superheated steam, and then flows into the turbine, and the nano-particles in the liquid-gas transition zone of the evaporator directly flow through the condenser through the throttle valve;

[0011] The high-temperature and high-pressure nano-mixed working medium expands in the turbine to do work, and then flows into the regenerator;

[0012] The nano-mixed working medium flowing from the turbine into the regenerator releases the heat it carries, and then flows into the condenser;

[0013] In the condenser, the expanded nano-mixed working medium is condensed into saturated liquid again, completing a waste heat recovery and work cycle.

[0014] The nano-mixed working medium is physically mixed from a metal organic framework material and 1,1,1,2-tetrafluoroethane, the mass ratio of the metal organic framework material is 0.1%-0.9%, and the metal organic framework material is one of Cr-MIL-101 and Mg-MOF-74.

[0015] In a third aspect, the present application also provides a mixed working medium for recovering waste heat of an engine, comprising a metal organic framework material and 1,1,1,2-tetrafluoroethane, and the mass ratio of the metal organic framework material is 0.1%-0.9%.

[0016] The metal organic framework material is one of Cr-MIL-101 and Mg-MOF-74.

[0017] The application discloses an engine waste heat recovery nanometer mixed working medium, a system and a method thereof, and adopts a nanometer mixed working medium which is physically mixed by a metal organic framework material and 1,1,1,2-tetrafluoroethane, wherein the mass proportion of the metal organic framework material is 0.1%-0.9%, and the metal organic framework material is one of Cr-MIL-101 and Mg-MOF-74; the waste heat recovery method is as follows: the nanometer mixed working medium is pressurized by a working medium pump, adsorption occurs between the organic working medium 1,1,1,2-tetrafluoroethane and the metal organic framework material Cr-MIL-101 or Mg-MOF-74, and then the nanometer mixed working medium flows through a regenerator; in the regenerator, desorption occurs between 1,1,1,2-tetrafluoroethane and the Cr-MIL-101 or Mg-MOF-74 in the nanometer mixed working medium flowing from the working medium pump, the nanometer mixed working medium absorbs heat from the nanometer mixed working medium at the outlet of a turbine, and then flows through an evaporator; in the evaporator, desorption occurs between 1,1,1,2-tetrafluoroethane and the Cr-MIL-101 or Mg-MOF-74, the nanometer mixed working medium absorbs heat released by an all-terrain vehicle engine, becomes high-temperature and high-pressure saturated steam or superheated steam, and then flows through the turbine, and part of the nanometer particles in a liquid-gas transition zone in the evaporator directly flow through a condenser through a throttle valve; in the turbine, desorption or adsorption occurs between 1,1,1,2-tetrafluoroethane and the Cr-MIL-101 or Mg-MOF-74, the nanometer mixed working medium in a high-temperature and high-pressure state expands to do work, and then flows through the regenerator; in the regenerator, adsorption occurs between 1,1,1,2-tetrafluoroethane and the Cr-MIL-101 or Mg-MOF-74 in the nanometer mixed working medium flowing from the turbine, the nanometer mixed working medium releases heat carried by itself, and then flows through the condenser; in the condenser, the expanded nanometer mixed working medium is condensed into a saturated liquid again, adsorption occurs between 1,1,1,2-tetrafluoroethane and the Cr-MIL-101 or Mg-MOF-74, and a waste heat recovery work cycle is completed. The nanometer mixed working medium is used as the working medium of the organic Rankine cycle, the engine waste heat can be effectively recovered, the mixed mode of 1,1,1,2-tetrafluoroethane and the Cr-MIL-101 or Mg-MOF-74 has higher thermal efficiency than other mixed working media, the system performance of the organic Rankine cycle is effectively improved, the heat of the working medium flowing out of the turbine can be effectively utilized through the regenerator, the temperature of the working medium entering the evaporator is improved, the working medium continues to be heated into saturated steam or superheated steam after entering the evaporator from the regenerator, the heat recovery capacity of the organic Rankine cycle is improved through the nanometer mixed working medium, the multiple engines can work at a suitable temperature, and the service life of the heat source components of the all-terrain vehicle is prolonged. BRIEF DESCRIPTION OF DRAWINGS

[0018] In order to make the technical solutions of the embodiments of the present application or the prior art clearer, the accompanying drawings needed in the embodiments or prior art description will be briefly introduced. Obviously, the accompanying drawings in the following description are only some embodiments of the present application, and for those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0019] Figure 1 is a structural schematic diagram of an engine waste heat recovery system of the present application.

[0020] Figure 2 is a structural schematic diagram of an engine waste heat recovery system of the present application not containing an evaporator.

[0021] Figure 3 is a schematic diagram of adsorption isotherm between 1,1,1,2-tetrafluoroethane and Cr-MIL-101.

[0022] Figure 4 is a schematic diagram of adsorption isotherm between 1,1,1,2-tetrafluoroethane and Mg-MOF-74.

[0023] Figure 5 is a Langmuir model parameter table.

[0024] Figure 6 is a performance schematic diagram table of the nano mixed organic working medium in embodiments 1-4 of the present application.

[0025] 1-working medium pump, 2-heat regenerator, 3-evaporator, 4-turbine, 5-condenser, 6-throttle valve. DETAILED DESCRIPTION

[0026] The embodiments of the present application are described in detail below, and examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference signs represent the same or similar elements or elements having the same or similar functions throughout. The embodiments described below by referring to the accompanying drawings are exemplary and are intended to explain the present application, and cannot be understood as a limitation of the present application.

[0027] Please refer to Figures 1-6 , in a first aspect, the present application provides an engine waste heat recovery system, comprising a working medium pump 1, a heat regenerator 2, an evaporator 3, a turbine 4, a condenser 5 and a throttle valve 6.

[0028] The regenerator 2 and the working medium pump 1 are communicated and located at the side of the working medium pump 1; the evaporator 3 and the regenerator 2 are communicated and located at the side of the evaporator 3; the turbine 4 is respectively communicated with the evaporator 3 and the regenerator 2 and located between the evaporator 3 and the regenerator 2; the condenser 5 is respectively communicated with the regenerator 2 and the working medium pump 1 and located between the regenerator 2 and the working medium pump 1; the throttle valve 6 is respectively communicated with the evaporator 3 and the condenser 5 and located between the evaporator 3 and the condenser 5.

[0029] In the embodiment, the engine waste heat recovery system of the application adopts a nano mixed working medium which is physically mixed by metal organic framework material and 1,1,1,2-tetrafluoroethane, the mass ratio of the metal organic framework material is 0.1%-0.9%, and the metal organic framework material is one of Cr-MIL-101 and Mg-MOF-74; the waste heat recovery method is as follows: the nano mixed working medium is pressurized by the working medium pump 1, adsorption occurs between the organic working medium 1,1,1,2-tetrafluoroethane and the metal organic framework material Cr-MIL-101 or Mg-MOF-74, and then the nano mixed working medium flows through the regenerator 2; in the regenerator 2, desorption occurs between 1,1,1,2-tetrafluoroethane and Cr-MIL-101 or Mg-MOF-74 in the nano mixed working medium flowing from the working medium pump 1, the nano mixed working medium absorbs the heat from the outlet of the turbine 4, and then flows through the evaporator 3; in the evaporator 3, desorption occurs between 1,1,1,2-tetrafluoroethane and Cr-MIL-101 or Mg-MOF-74, the nano mixed working medium absorbs the heat released by the all-terrain vehicle engine and becomes high-temperature and high-pressure saturated steam or superheated steam, and then flows through the turbine 4; part of the nano particles in the liquid-gas transition zone in the evaporator 3 directly flows through the condenser 5 through the throttle valve 6; in the turbine 4, desorption or adsorption occurs between 1,1,1,2-tetrafluoroethane and Cr-MIL-101 or Mg-MOF-74, the nano mixed working medium in the high-temperature and high-pressure state expands to do work, and then flows through the regenerator 2; in the regenerator 2, adsorption occurs between 1,1,1,2-tetrafluoroethane and Cr-MIL-101 or Mg-MOF-74 in the nano mixed working medium flowing from the turbine 4, the nano mixed working medium releases the heat carried by itself, and then flows through the condenser 5; in the condenser 5, the expanded nano mixed working medium is condensed into saturated liquid again, adsorption occurs between 1,1,1,2-tetrafluoroethane and Cr-MIL-101 or Mg-MOF-74, and one cycle of waste heat recovery work is completed.

[0030] In another embodiment, please refer to Figure 1The engine waste heat recovery system can omit the regenerator 2. After omitting the regenerator 2, the working fluid pump 1 is directly connected to the evaporator 3, and the turbine 4 is directly connected to the condenser 5. The waste heat recovery method is as follows: the nano-mixed working fluid is pressurized by the working fluid pump 1, and the organic working fluid 1,1,1,2-tetrafluoroethane adsorbs between itself and the metal-organic framework material Cr-MIL-101 or Mg-MOF-74, subsequently flowing through the evaporator 3. Inside the evaporator 3, 1,1,1,2-tetrafluoroethane desorbs between itself and Cr-MIL-101 or Mg-MOF-74, and the nano-mixed working fluid absorbs the heat released by the all-terrain vehicle engine. The vaporized material is converted into high-temperature, high-pressure saturated or superheated steam, which then flows through turbine 4. Some of the nanoparticles in the liquid-gas transition zone of evaporator 3 flow directly through condenser 5 via throttling valve 6. Inside turbine 4, 1,1,1,2-tetrafluoroethane undergoes desorption or adsorption with Cr-MIL-101 or Mg-MOF-74, and the high-temperature, high-pressure nano-mixed working fluid expands and performs work, then flows through condenser 5. In condenser 5, the expanded nano-mixed working fluid is condensed again into a saturated liquid, and 1,1,1,2-tetrafluoroethane undergoes adsorption with Cr-MIL-101 or Mg-MOF-74, completing one waste heat recovery work cycle.

[0031] This invention discloses an engine waste heat recovery system that utilizes a nano-mixed working fluid as the working fluid for an organic Rankine cycle. This system effectively recovers engine waste heat. The use of a mixture of 1,1,1,2-tetrafluoroethane and Cr-MIL-101 or Mg-MOF-74 offers higher thermal efficiency compared to other mixed working fluids, effectively improving the system performance of the organic Rankine cycle. The regenerator 2 effectively utilizes the heat from the working fluid exiting the turbine 4, increasing the temperature of the working fluid entering the evaporator 3. After exiting the regenerator 2, the working fluid continues to heat up in the evaporator 3, becoming saturated steam or superheated steam. The combined heat transfer through the regenerator 2 and evaporator 3 increases the flow rate of the nano-mixed working fluid, improving the output shaft power. By enhancing the heat recovery capacity of the organic Rankine cycle through the nano-mixed working fluid, the system ensures that multiple engines operate at suitable temperatures while also extending the service life of the heat source components of the all-terrain vehicle.

[0032] Secondly, the present invention also provides a method for recovering waste heat from an engine, comprising:

[0033] S1 nano-mixed working fluid is pressurized by working fluid pump 1 and enters regenerator 2;

[0034] The nano mixed working medium is physically mixed by metal organic framework material and 1,1,1,2-tetrafluoroethane, the mass ratio of the metal organic framework material is 0.1%-0.9%, the metal organic framework material is one of Cr-MIL-101 and Mg-MOF-74; the nano mixed working medium is pressurized by the working medium pump 1, the adsorption occurs between the organic working medium 1,1,1,2-tetrafluoroethane and the metal organic framework material Cr-MIL-101 or Mg-MOF-74, and then the nano mixed working medium flows through the regenerator 2.

[0035] S2 The nano mixed working medium absorbs the heat of the nano mixed working medium from the outlet of the turbine 4 in the regenerator 2, and then flows into the evaporator 3.

[0036] In the regenerator 2, the desorption occurs between 1,1,1,2-tetrafluoroethane and Cr-MIL-101 or Mg-MOF-74 in the nano mixed working medium flowing out of the working medium pump 1, the nano mixed working medium absorbs the heat of the nano mixed working medium from the outlet of the turbine 4, and then flows through the evaporator 3.

[0037] S3 The nano mixed working medium absorbs the heat released by the engine in the evaporator 3 to become high-temperature and high-pressure saturated steam or superheated steam, and then flows into the turbine 4, and part of the nano particles in the liquid-gas transition zone in the evaporator 3 directly flow through the condenser 5 through the throttle valve 6.

[0038] In the evaporator 3, the desorption occurs between 1,1,1,2-tetrafluoroethane and Cr-MIL-101 or Mg-MOF-74, the nano mixed working medium absorbs the heat released by the all-terrain vehicle engine to become high-temperature and high-pressure saturated steam or superheated steam, and then flows through the turbine 4, and part of the nano particles in the liquid-gas transition zone in the evaporator 3 directly flow through the condenser 5 through the throttle valve 6.

[0039] S4 The high-temperature and high-pressure nano mixed working medium expands to do work in the turbine 4, and then flows into the regenerator 2.

[0040] In the turbine 4, the desorption or adsorption occurs between 1,1,1,2-tetrafluoroethane and Cr-MIL-101 or Mg-MOF-74, the high-temperature and high-pressure nano mixed working medium expands to do work, and then flows through the regenerator 2.

[0041] S5 The nano mixed working medium flowing from the turbine 4 into the regenerator 2 releases the heat carried by itself, and then flows into the condenser 5.

[0042] In the regenerator 2, the adsorption occurs between 1,1,1,2-tetrafluoroethane and Cr-MIL-101 or Mg-MOF-74 in the nano mixed working medium flowing from the turbine 4, the nano mixed working medium releases the heat carried by itself, and then flows through the condenser 5.

[0043] S6 In the condenser 5, the expanded nanometer mixed working medium is condensed into saturated liquid again, and the adsorption between 1,1,1,2-tetrafluoroethane and Cr-MIL-101 or Mg-MOF-74 occurs, completing a waste heat recovery work cycle.

[0044] In the condenser 5, the expanded nanometer mixed working medium is condensed into saturated liquid again, and the adsorption between 1,1,1,2-tetrafluoroethane and Cr-MIL-101 or Mg-MOF-74 occurs, completing a waste heat recovery work cycle.

[0045] The application will be further described in detail below in combination with the drawings and specific examples.

[0046] Example 1: The mass fraction of Cr-MIL-101 nanoparticles in the nanometer mixed working medium is 0.9%, and after physical mixing in the organic working medium 1,1,1,2-tetrafluoroethane, it is used as the basic organic Rankine cycle working medium for treating the waste heat of the engine of an all-terrain vehicle.

[0047] Example 2: The mass fraction of Cr-MIL-101 nanoparticles in the nanometer mixed working medium is 0.9%, and after physical mixing in the organic working medium 1,1,1,2-tetrafluoroethane, it is used as the regenerative organic Rankine cycle working medium for treating the waste heat of the engine of an all-terrain vehicle.

[0048] Example 3: The mass fraction of Mg-MOF-74 nanoparticles in the nanometer mixed working medium is 0.9%, and after physical mixing in the organic working medium 1,1,1,2-tetrafluoroethane, it is used as the basic organic Rankine cycle working medium for treating the waste heat of the engine of an all-terrain vehicle.

[0049] Example 4: The mass fraction of Mg-MOF-74 nanoparticles in the nanometer mixed working medium is 0.9%, and after physical mixing in the organic working medium 1,1,1,2-tetrafluoroethane, it is used as the regenerative organic Rankine cycle working medium for treating the waste heat of the engine of an all-terrain vehicle.

[0050] The adsorption model of Mg-MOF-74 and Cr-MIL-101 and 1,1,1,2-tetrafluoroethane in the above examples 1-4 is designed as a Langmuir adsorption equilibrium model, as shown in the following formula.

[0051]

[0052] In the formula, ω i is the adsorption amount of the adsorbate in the adsorbent (unit: g / g); T is the temperature (unit: K); pi is the partial pressure of the adsorbate (unit: bar); IP1 to IP4 are different regression isotherm parameters. The model parameters are shown in Table 3.

[0053] The working medium of the above embodiment is used as a high-temperature tail gas treatment cycle working medium, and a high-temperature tail gas is used as a heat source to exchange heat in a Rankine cycle system, and the design conditions of the high-temperature tail gas Rankine cycle are as follows: the ambient temperature is 20 DEG C, the high-temperature heat source temperature is 100-200 DEG C, the evaporation pressure is 0.1-10 MPa, the isentropic thermal efficiency of the turbine 4 is assumed to be 95%, and the isentropic thermal efficiency of the working medium pump 1 is assumed to be 85%.

[0054] In combination Figure 2 , the system involved in the waste heat recovery method embodiments 1 and 3 of the basic formula Rankine cycle nano-mixed working medium 1,1,1,2-tetrafluoroethane and Cr-MIL-101 or Mg-MOF-74 is composed of a working medium pump 1, an evaporator 3, a turbine 4, a condenser 5 and a throttle valve 6. After being pressurized by the working medium pump 1, the nano-mixed working medium absorbs the heat of the engine exhaust in the evaporator 3, becomes high-temperature and high-pressure saturated steam or superheated steam, enters the turbine 4 to expand and do work, and the expanded organic working medium enters the condenser 5 to condense into saturated liquid.

[0055] In combination Figure 1 , the system involved in the waste heat recovery method embodiments 2 and 4 of the regenerative Rankine cycle nano-mixed working medium 1,1,1,2-tetrafluoroethane and Cr-MIL-101 or Mg-MOF-74 is composed of a working medium pump 1, a regenerator 2, an evaporator 3, a turbine 4, a condenser 5 and a throttle valve 6. After being pressurized by the working medium pump 1, the nano-mixed working medium absorbs the heat of the nano-mixed working medium from the outlet of the turbine 4 in the regenerator 2, then absorbs the heat of the engine exhaust in the evaporator 3, becomes high-temperature and high-pressure saturated steam or superheated steam, enters the turbine 4 to expand and do work, and the expanded organic working medium enters the condenser 5 to condense into saturated liquid.

[0056] In a third aspect, the present application also provides a mixed working medium for recovering waste heat of an engine, comprising a metal organic framework material and 1,1,1,2-tetrafluoroethane, and the mass ratio of the metal organic framework material is 0.1%-0.9%.

[0057] The metal organic framework material is one of Cr-MIL-101 and Mg-MOF-74.

[0058] The engine waste heat recovery mixed working medium critical pressure of the application is suitable, the slip temperature is large during phase change, meets the all-terrain vehicle engine waste heat recovery requirement, and the cycle performance is excellent, the reason is that compared with conventional materials, the porosity of the metal organic framework material is high, the density is low and the specific surface area is large, a certain amount of metal organic framework material nanoparticles is added in the organic working medium, the surface energy change between the fluid and the metal organic framework material is used to realize the energy storage and output, the heat storage capacity of the fluid working medium is improved, so that the system efficiency can be improved. When the mass fraction of the metal organic framework material is 0.9% under the rated working condition of the engine at the ambient temperature 25 DEG C, the maximum thermal efficiency of the nanometer mixed working medium is improved by 21.59% for the regenerative organic Rankine cycle system, the maximum net output power is improved by 23.72%, and the maximum efficiency is improved by 28.52%.

[0059] The above only discloses a preferred embodiment of the application, of course, cannot limit the scope of the application, those skilled in the art can understand that the whole or part of the above-mentioned embodiment is realized, and the equivalent changes made according to the claims of the application still belong to the scope covered by the application.

Claims

1. A method for recovering waste heat from an engine, characterized in that, The system includes an engine waste heat recovery system, which comprises a working fluid pump, a regenerator, an evaporator, a turbine, a condenser, and a throttle valve. The regenerator is connected to the working fluid pump and is located on the side of the working fluid pump; the evaporator is connected to the regenerator and is located on the side of the evaporator; the turbine is connected to both the evaporator and the regenerator and is located between the evaporator and the regenerator; the condenser is connected to both the regenerator and the working fluid pump and is located between the regenerator and the working fluid pump. The throttling valve is connected to both the evaporator and the condenser, and is located between the evaporator and the condenser. The engine waste heat recovery method includes: The nano-mixed working fluid is pressurized and enters the regenerator via a working fluid pump; The nano-mixed working fluid absorbs heat from the turbine outlet within the regenerator and then flows into the evaporator; The nano-mixed working fluid absorbs the heat released by the engine in the evaporator, becoming high-temperature and high-pressure saturated steam or superheated steam, which then flows into the turbine. Some of the nanoparticles in the liquid-gas transition zone in the evaporator flow directly through the condenser through the throttle valve. The high-temperature and high-pressure nano-mixed working fluid expands and performs work inside the turbine, and then flows into the regenerator; The nano-mixed working fluid flowing from the turbine into the regenerator releases the heat it carries, and then flows into the condenser; In the condenser, the expanded nano-mixed working fluid is condensed again into a saturated liquid, completing one waste heat recovery and work cycle; The nano-mixed working fluid is physically mixed with a metal-organic framework material and 1,1,1,2-tetrafluoroethane. The metal-organic framework material accounts for 0.1%-0.9% of the mass, and the metal-organic framework material is one of Cr-MIL-101 and Mg-MOF-74.

2. A mixed working fluid for engine waste heat recovery, applied to the engine waste heat recovery method as described in claim 1, characterized in that, It includes metal-organic framework materials and 1,1,1,2-tetrafluoroethane, wherein the metal-organic framework materials account for 0.1%-0.9% by mass.

3. The mixed working fluid for engine waste heat recovery as described in claim 2, characterized in that, The metal-organic framework material is one of Cr-MIL-101 and Mg-MOF-74.

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