Carbon dioxide engine by utilising ambient heat and high-pressure sink

Abstract

A Carbon dioxide (CO2) engine used to generate energy comprising: a piston 7 in a piston chamber 22 driven via the expansion of carbon dioxide 21 when it changes phase from a liquid to a gas using amb

Description

The aim is to develop an advanced engine system, which uses Carbon Dioxide as working fluid for supplying uninterruptable power for Power stations, Automobiles, Data Centers, Manned and Unmanned Drones and other Automobile applications. Where the current battery power sources are inadequate for the high demand of power usage in war fronts and operations in remote locations. The proposed system should power the UAVS and unmanned robotics systems in future war fare and remote locations. The types of operation possible by UAS / RPAS may extend the overall flight duration from hours to days, months and possibly years. Current Art In the conventional Rankine cycle, we are inputting the heat from heat sources like diesel, coal and petrol and the working fluids such as water is expanded to gas, where it is converted to energy using a turbine / piston and rejected the unwanted heat to a low heat sink. Here the heat source is above 300 degrees Celsius, and sink is ambient temperature. Conventionally we design the heat source in higher temperature and set the ambient temperature as sink. The efficiency of this system is very low as heat loss is about 60 percent in the burning stage. For example, only 30% of heat is utilized by burning wood or coal to energy. An overall wastage of 70% heat. In Conventional IC engines and Steam turbines are utilizing only 40 to 50% of heat supplied to the engine. The rest is dissipated as heat (Pauken, 2011 p 117). Our aim is to develop a technology which can utilize the ambient heat for energy generation along with cold for air conditioning and engine cooling, which is the bi product of the concept. Currently the efficiency of heat engines is in the range 30 to 40%. This is because half of the heat input is rejected to the atmosphere from the system by the Radiator. We are using the air conditioner in automobiles throughout the year in tropical areas of the world where70% of the population lives. This air-conditioner rejects heat in two ways. First the load of the Engine increases to 25% when we switch on AC. This makes the engine to reject 25% more heat and another heat is the heat suck by the AC from the passenger area or cooling area of the Automobiles. So, it constitutes another heat from the automobiles. There is a huge amount of low-grade heat is dissipated to atmosphere from each automobile. Here I am focusing on this challenge- How we can utilize the ambient heat of the atmosphere and converted to useful energy for drones and automobiles for uninterrupted power? Summary of my Innovation Here I am redesigning the traditional concept of higher temperature source and normal ambient temperature heat sink to normal atmospheric temperature heat source to a high-pressure heat sink. The advantage is the source is infinite as the low boiling point working liquid sucks heat from atmosphere for piston expansion and the rejected heat is sucked by high pressure heat sink same as the principle of a refrigerator were high pressure working fluid rejects heat to the atmosphere. Here the waste heat sucked is return to the source for next cycle. Conventionally we design the heat source in higher temperature say above 300 degrees Celsius and set the ambient temperature as sink. But here I am redesigning the system by setting heat source temperature at ambient temperature and creating heat sink using high pressure system in ambient temperature to -12 Degree Celsius using anti-freeze Liquid or water as heat transfer liquid. Here I am redesigning a sink by pressurizing the working fluid to reject the heat in ambient temperature or the temperature we designed. There by we can create source and sink at ambient temperature. The sink is designed based on the refrigeration principle as gas compressed, it rejects heat to atmosphere. We can design the sink according to the ambient conditions by adjusting the pressure. This is the natural law of creating rain from ambient heat. Where the heat source is ambient atmosphere and sink is higher altitude with very low temperature. We can calculate the rejected heat and the energy needed for it. The secret source is the efficiency of refrigeration system with cop 1:4. Ei one unit of electrical energy can suck four unit of heat from the sink. Another advantage is the reduction of global warming by the absorption of heat from the atmosphere by each automobile using this technology. There by reducing the global warming and stabilizing the climate change. Global ambient heat is the fuel for this technology instead of fossil fuels. There by this idea is a zero-carbon propulsion system which utilizes natural energy abundant in atmosphere. In my innovation the heat source is ambient temperature and working fluid is High pressure liquid CO2, and the Sink is high pressure working gaseous fluid, which is pressurised using a high-pressure system. The advantage of the system is the heat source is ambient temperature which is an infinite source of energy ei ambient temperature of air. Here we use Carbon dioxide fluid with boiling point -78 degree Celsius and, it will absorb 500 kilojoules / kg of heat from the atmosphere at Critical Point of 31.1 degree Celsius and critical pressure of 73.8 Mpa and get expanded to gas in the piston- cylinder connected to a crank shaft and depart the energy to the fly wheel. Reference: Mollier Diagram of CO2 for obtaining the Data. I made a prototype for this part with a lawn mower engine and CO2 Fire Extinguisher which is 53.8bar (5.3 MPa) pressure. The extinguisher is connected via a hose to the cylinder -piston of the lawn mower and it starts working. Other working examples are CO2 cannisters for filling Bike tyres. This can be applied to any altitudes and sucks heat from atmosphere as fuel, thereby reducing global warming. Here I am expanding the liquid high-pressure CO2 from 7.3Mpa to 100 Kilo Pascals. Specific Volume of co2 at STP = 0.549. At Standard temperature and pressure 1kg of Co2 liquid turns to approximately 0.549 cubic meter of CO2 Gas. Work done =Pressure x Volume =7.3MPa x 0.5Cubic Meter...................Mollier Diagram =7.3xl000KPax0.5 Cubic Meter =3650 KN.............................................(1) This much power is generated by the piston for lKg of CO2 Expansion. Once the liquid is expanded it absorbs heat from the atmosphere or heat exchanger. Thus, the Antifreeze liquid cooled to -10 degree Celsius and connected to sink for heat exchange. Note: If we have a data centre or need refrigeration we can utilize the cooled antifreeze liquid for heat exchange. Now the next aim is return the gas to liquid using high pressure artificial refrigeration system. For example, the heat inside 1 kilo of expanded gas is 450 to 500 kilo joules. If we absorb 250 kilojoules, it turns to liquid again (Ref: Mollier Diagram). For sucking these 250 kilojoules of heat in ambient temperature, the gas is in 3.5 MPa so that it started to reject heat to zero degree Celsius. For this we use any automobile antifreeze liquid for heat transfer in heat exchanger. (Reference Mollier diagram). While passing through the exchanger at high pressure it turns to liquid. The volume of the liquid is equal to 0.001 cubic meter(lLitre / Kg). The artificially created sink which is by pressurising the gas to 3.5 MPA were the carbon dioxide gas turns to liquid in zero-to-five-degree Celsius temperature. Reference: Mollier Diagram of CO2. The work done by the compressor = Pressure x Volume Density of Liquid C02=900 kg / Cubic Meter Specific Volume of CO2 liquid = 0.001 m3 / Kg....................................Air Liquide .com The CO2 gas shrink from 0.5333m3 to 0.001 m3(1 litre) when it converted to liquid. Work done to pressurize the gas from STP to 3.5 MPA =3.5 MPa x0.0.533 m3 =3.5X1000KPaX 0.5331 = 1865 KN............................................(2) Once the gas is compressed it emits heat towards atmosphere. This heat is absorbed by the heat exchanger fluid and this heat is utilized to expand the piston for useful work and also utilize the vacuum created by condenser for useful work using James watts condensation chamber. Now we need to pressurize the liquid from 3.5 MPA to 7.3 MPa for a volume of 0.001 m3 Work done = Pressure x Volume = 3.8 MPA x 0.001 m3 -3. K N ................................................................................................... (3) Another advantage is the vacuum created by the change in fluid can be utilized for generating energy using James's watt vacuum chamber. Where the vacuum created can be used for power generation apart from the main piston power. The final advantage is the absorbed heat from the sink is feed to the heat source. To make the heat source always in ambient temperature. The background of the Invention and working principle. Look at Figure 1 on page 1 Imagine if we can create the above process in a box. The above process is created and modelled in ground level by cooling the working fluid artificially using a pressurized system. Step 1 Here we are pressurizing the gas (21) in chamber (22) using an external compressor (10). Firstly, the working fluid (21) in gaseous state at STP get pressurised in a chamber (22) which is connected to the piston (7). The piston is compressed by the pressure from a compressor / turbine system (10). After the desired pressure is reached the valve (8) is closed. Here we are using the Mollier diagram of CO2 to find out the compressor pressure needed to convert the gas to liquid. We can see the water temperature is approximately at 0 to 5 degrees for a pressure of 3.5 MPA from Mollier Chart given on reference page. Step 2 The pressurized gas (21) flows to the heat exchanger (16) when we open the valve (15). In the Heat exchanger or sink (16), the gas turns to liquid and now this liquid (17) is collected in the chamber (18) which is connected to sink(16). When the fluid turns to liquid it creates a vacuum in chamber (22) which drives piston (7) downwards creating another work. Step 3 The cold liquid coming out of the sink is first collecting in a chamber (18) and then fed to the liquid pump (1) via an insulated high pressure pipe (19 ) to pressurize the liquid (17). This liquid is moved towards cylinder chamber (20). When the valve (2) opens the liquid rushed into the chamber (20) and get expanded in the chamber and pushes the piston (4) to drive the crankshaft (5) which is connected to the fly wheel (6). The energy is transferred to the shaft. The process is repeated in the closed cycle. Now the valve (14) opens, and the expanded gas is moved to chamber (22) as the crank shaft drives piston (5) down wards. Which is ready for next cycle. Step 4 The rejected heat from sink (16) is connected via pipes (25) to the expansion chamber (20) for heating up the working fluid for next expansion. The temperature is amplified and rejected to the heat exchanger (26) by the refrigerator (12). For example, the carbon dioxide refrigeration system can suck heat as low as -20 degree Celsius from sink and reject heat to 120 degrees Celsius to source with cop 4. (www.Danfoss .com / Refrigeration case studies). Step 5 when we open the valve (8), the compressed air (26) which is at 3.5 MPA in chamber ( 27) is released into the compressor cum turbine( 10 ) which can regenerate around 50% of energy used for compressing the gas by compressor which is connected to a motor cum generator(9). Analysis of power input, heat absorbed, Power output and Heat rejected. Look at the figure 1 attached to analyse the basic mathematical model of the system. Working fluid Here we are choosing the Carbon dioxide as the working fluid. The latent heat of vaporization of Carbon dioxide at critical point is 500 kilojoules at 32 Degree Celsius. In this energy level Carbon dioxide is in gas. The latent heat of fusion is 250 kilo joules, and this is the energy where the gas becomes liquid at 3.5MPA @1 Degree Celsius. The liquid saturation point is between these two energy levels and is approximately 250 Kilo joules. So, if we suck the 500-250 = 250kilo joules, CO2 gas turns to liquid from gas. Reference: Mollier Diagram of CO2. Step 1 - Work output As we know the expansion ratio of Co2 is 1:500 at STP. One Kilogram of CO2 liquid turns to 500 litres of CO2 gas or 0.5 Cubic meter of CO2 gas. The energy released when to 1kg liquid at 7.3 MPA turns to gas at STP = Pressure x Volume = 7300KPAX0.5 Cubic Meter =3650 KN Step 2 -work input Turning back gas to Liquid Now the gas is pressurized to 3.5 MPA by the compressor system, and the volume shrinks to 1 litre liquid @ 5 degree Celsius. Work done = Pressure x Volume = 3.5 MPA xO.500 = 3500KPAx0.500 Cubic Meter = 1925 Kilo Newton. Moreover, the gas-to-gas pressurization reduces the volume Equivalent to 0.01 cubic meter / kg as per the Mollier diagram for Co2(ldeal gas Law), and can utilize it for energy generation same as James Watt condenser concept for energy generation. (D. Ziviani 1, A. Desideri2, V. Lemort2, M. De Paepel, M. van den Broekl, (2015) p10). This reduced volume turns to 0.001 cubic meter, when gas turns to liquid CO2. Approximately 1 litre of liquid CO2 at 3.5 Mpa. There creates a vacuum volume of 0.01-0.001 cubic meter when gas turned to liquid which is approximately 0.01 cubic meter. Step 3 - Work output 2 The work done by the vacuum chamber = Vacuum Pressure x volume = 3.5 MPA x 0.01 cubic meter =3500kpaX .01 Cubic Meter =35 KN Now the next step is as soon as the gas is pressurised it then passes through a heat exchanger and dissipates its heat to the heat exchanger which is liquid cooled at zero degree Celsius. Step 4 -Work output 3 The next step is to release the high-pressure air to a turbine cum compressor. This compressor acts as a turbine when high pressure air is fed to it. The work done by the pressure on compressor cum turbine = Pressure x Volume =3.5 MPa x 0.7 Cubic Meter =2450 KN Assuming 50% cycle efficiency, Net power recovered 2450x0.5 =1225 KN (Approx)................................................(.3) Step 5 -Work input 2 Our aim is to suck the energy or heat by using an external refrigerator. As we know the coefficient of performance of a refrigeration system is 1:5. For every 1 unit of energy input four to five unit of heat energy is absorbed by the refrigeration system marked 12 in figure 1. The cooling part (16) of the refrigeration system (12) is connected to the vacuum chamber (22) via pipe and a valve (15). When valve opens, the chamber (22) becomes vacuum when the gas turned to liquid form in heat exchanger (16). So input energy required or work done by the refrigerator for sucking 250 kilojoules of heat energy = 250 / 5 = 50 kilo joules. This is the input energy required by the refrigeration unit to make the vacuum chamber vacuum. As once the heat is sucked from the system, the working fluid in gaseous state turns to liquid in heat exchanger (16). (Cop of Refrigerator is 1:5 as 25 kilo joules of work input can suck 125 kilojoules of heat from the sink as low as -78 degree to 15 degree Celsius) (Reference Mollier diagram of Carbon dioxide system). 2) The power output by the Main Piston This is the work done by the piston (5) or expansion chamber to extract work by the expansion of the fluid in Chamber(20) in the figure 1. Work done by 1 kilogram of fluid in the expansion chamber or turbine =pressure x volume = 7500 kilo Pascalx0.515 cubic meter =3862 kilo joules This is the power output by the turbine or expansion chamber. Heat input and power output from the system. Heat input is the heat absorbed by the system to change from liquid to gas and is equal to the latent heat of vaporization. Heat absorbed at 7.3 MPA =500 kilo joules / Kg....................................Mollier Diagram This heat is the heat absorbed by the system from external sources. Since the boiling point of CO2 I is -78 degree Celsius, It will absorb heat from atmosphere to change from liquid to gas. Also, we are providing the rejected heat from the sink (16) to heat exchanger marked (26) using the external refrigeration system (12). Once it changes to gas, the volume increases to 515 times as the expansion ratio of Carbon dioxide is 0.515m3 / kg Work done by 1 kilogram of fluid in the expansion chamber or turbine =pressure x volume = 7.3 MegaPascalxO.515 cubic meter = 7300 kilo Pascalx0.50 cubic meter =3759.5 kilo Joules..............................(1) This is the Work output by the piston (5) or expansion chamber. Heat input to the system. The heat absorbed by the system is the heat needed for changing the phase from liquid to gas. The heat needed for the latent heat of vaporization=500 kilojoules-Latent heat of saturation liquid =500-250 =250 Kilo joules @5 MPA. Ref: Mollier Diagram. Heat output from the system. The heat rejected from the system is the heat rejected by the gas in the vacuum chamber (22) to make it cool for changing the gas to liquid. Since a fluid changes gas to liquid, we must absorb the heat from the gas. Here the amount of heat needed to absorb to change the state is 250 kilojoules. This heat is absorbed using external refrigeration (12) through heat exchanger (16). The heat absorbed by the external refrigerator (16) =250 kilojoules. This heat is added and amplified to the Heat absorption source (26) by transferring heat from the vacuum chamber to sink to the expansion chamber by the refrigerator (16). Net heat output from the system is zero apart from transmission and radiation losses. Because the rejected heat is transferring to the heat absorption chamber (26). The net power output from the system Work output= Work output from expansion chamber (5)+ power output from vacuum chamber(7) + Regenerative output from compressor turbine(lO) =3659KN+35 kilo Newton +1225 Kilo Newton. = 4919 KN Work input=work input for Compressed Sink (7) + Power for the refrigeration (12) +Power input for liquid pump (1) for compressing Liquid. = 2450 KN +50 KN+ 3.5KN =2503.5 KN Net work out put =Work output- Work input =4919-2503.5 kilojoules = 2415.5 KN Working Fluid = Carbon dioxide (Boiling Point (TH) -78.46-degree Celsius, Latent heat of vaporization= 500 Kilojoules. This is the theoretical Network output of the system using Carbon dioxide as the working fluid and a standard Carbon dioxide refrigeration system for sucking heat. Due to the unavailability of data, here I selected some of the common fluid whose parameters are well known. We can change the working fluid if we can have data base of the fluids which would suit best to the application Working Fluid Boiling point in degree Celsius Latent heat of vaporization (KJ) Latent heat of Fusion Enthalpy(kJ) Expansion Ratio Water 100 2200 419 1.000m3 / kg Nitrogen -195 199 25.72 0.87 m3 / kg Methane -161 510.83 88.6 1.5m3 / kg Ethylene -103 482.2 119.45 0.8687m3 / kg Silane SiH4 -112 377.7 20.77 0.7567m3 / kg Data Tablel Here we are analysing the system using working fluid Carbon dioxide (Reference Mollier Chart). Here we are designing the system at the critical point of CO2. Working Fluid= (Boiling Point = -78 degrees Celsius, Latent heat of vaporization=500 Kilojoules / Kg, Critical Pressure =7.3Mpa. Expansion ratio at STP =1:518 Reference: Encyclopaedia.airliquide.com) Q input QH= 515 kilojoules at TH, 15 degree sucks this heat from air as the boiling point of working fluid is -78.46 degree Celsius). TH=15 degree Celsius. Work OUT Expansion =pressure x volume = 7300 kilo Pascal's x0.515 m3= 3759.5 kilo joules WORKOUT Vacuum =35 Kilojoules ( As the fluid turns back to liquid by the absorption of heat by refrigerator as CO2 Refrigerant with boiling point -78.45 degree Celsius depending upon pressure). Work input = 50 kilo Joules. (Cop of Refrigerator is 1:5 as 50 kilojoules of work input can suck 250 kilojoules of heat from the sink the CO2 vapour changes to liquid as low as -78 degree to 15 degree Celsius depending upon pressure) (Reference ph diagram of Carbon dioxide refrigeration system). Conclusion The power output from the system There are three power output from the system. 1) The power output by the piston (5). This is the work done by the piston and expansion chamber (22) to extract work by the expansion of the fluid. Here the working fluid expanded to several times and work is delivered to the piston. Here the heat is absorbed from the engine which makes the engine cool. If there is no heat from the engine, the heat will be absorbed from the atmosphere as the boiling point of the liquid is less than the ambient temperature. The working fluid turns to gaseous state (23) and moved to gas chamber marked (22) in figl. The heat can be absorbed from Data Centres, Refrigeration Units, Air conditioning units and freezers. 2) The vacuum power output by the condensation of the liquid. This is the work extracted from the vacuum chamber (22), when the working fluid turns from gas to liquid in the heat exchanger. In this section first the vapour coming out from the gas chamber (23) is collected in the chamber (22). The chamber is attached to a piston (7). The vapour drives the piston (7) backwards. The high-pressure compresses the piston to 3.5 MPA. The external refrigeration system which marks as (12) with heat exchanger (16) in figure, cools the chamber. Now the gaseous form turns to liquid and shrinks its volume in low temperature and creates a huge vacuum. This vacuum is utilized by the piston (7) connected to the cylinder for power generation. This part is same concept of James watt steam engine, where he utilizes external cooling chamber for creating vacuum. 3) The pressurised air returned to turbine compressor (10) to generate some energy for next cycle. 4)The heat sucked by the refrigeration system is rejected to the heat exchanger marked (26) for the next cycle. If there is excess heat is available in the engine and need engine cooling / refrigeration, we can divert the heat sucked from the vacuum chamber to the atmosphere rather than feeding back to the system. As the refrigerator will push the heat from the system. References D. Zivianil, A. Desideri2, V. LemortZ, M. De Paepel, M. van den Broekl; Low-order models of a single-screw expander for organic Rankine cycle applications: IOP Conf. Series: Materials Science and Engineering 90 (2015) 01206. Echogen Power Systems LLC 365 Water St. Akron, OH 44308 U.S.A, www.echogen.com I Saavedra, J C Bruno and A Coronas; Thermodynamic optimization of organic Rankine cycles at several condensing temperatures: case study of waste heat recovery in a natural gas compressor station. Michael Persichilli, Alex Kacludis, Edward Zdankiewicz, and Timothy: Supercritical CO2 Power Cycle Developments and Commercialization: Why sCO2 can Displace Steam. Pauken M, 2011 Thermodynamics for Dummies, John Wiley and Sons [NJ] 2011. R.Long,Y. J.BAo, X.M Huang,Energy analysis and working fluid selection of organic Rankine cycle for low grade waste heat recovery. S. Masheitil, B. Agnew2 and S. Walker2, An Evaluation of R134a and R245fa as the Working Fluid in an Organic Rankine Cycle Energized from a Low Temperature Geothermal Energy Source. S. Hani, Jong Beom Seol and Bum-Seog Choi2,*Development of a 200 kW ORC radial turbine for waste heat recovery. h tt p: / / h e a t p u mpingteg h no | ogi e s. p rg / p u b hcs t io n s. http: / / www,dai^ Mollier Diagram of Carbon dioxide cycle SS: ■ Sb! --- ------------__—............... .. . iW

Claims

1. C02 Engine which works on the pressurized Carbon dioxide liquid expanded to gas in piston chamber generates energy by absorbing ambient heat from heat source and the expanded gas pressurized and feed to sink rejecting heat in heat exchanger changes to liquid again in a closed system.

2. CO2 Engine according to claiml, in which the proposed system is designed by setting heat source temperature at ambient temperature and high pressure for sucking infinite source of heat energy from atmosphere as fuel and creating pressurized heat sink to reject heat to ambient temperature.

3. CO2 Engine according to claim 1, in which the vacuum created by the change in fluid in heat exchanger can be utilized for generating energy using James watt vacuum chamber where the vacuum created can be used for power generation apart from the main piston power.

4. CO2 Engine according to claim 1, in which the absorbed heat from the sink is amplified by the refrigerator and feed to the heat source thereby make the heat source always higher than ambient temperature for superheating the fluid.

5. CO2 Engine according to claim 1, the byproduct of the process is cold energy by the expansion of liquid carbon dioxide which can be used for refrigeration and air conditioning purposes.

6. CO2 Engine according to claim 1, the compressed air used for pressurising the CO2 gas can be used for regenerating power in a compressor cum turbine.13

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