ENHANCEMENT OF REFRIGERATION EFFECT USING FLUE GASES FROM CHIMNEY

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1 International Journal of Mechanical Engineering and Technology (IJMET) Volume 9, Issue 4, April 2018, pp , Article ID: IJMET_09_04_041 Available online at ISSN Print: and ISSN Online: IAEME Publication Scopus Indexed ENHANCEMENT OF REFRIGERATION EFFECT USING FLUE GASES FROM CHIMNEY Sukhvinder Singh, Chandra Pavan, Raghavendra, Lokesh kumar Department of Mechanical Engineering, Koneru Lakshmaiah Educational Foundation, Vaddeswaram, Guntur, Andhra Pradesh, India. Naveen Janjanam* Assistant Professor, Department of Mechanical Engineering, Koneru Lakshmaiah Educational Foundation, Vaddeswaram, Guntur, Andhra Pradesh, India. ABSTRACT Present work is focused on finding out the way to control the release of greenhouse effect gases. Global annual mean survey says, the CO 2 concentration has substantial increment of 45%. Frequently from the start of the industrial revolution, effect of greenhouse gases on environment is more so it requires necessary action to control the percentage of gases. Keeping in view of this point, flue gases which are released from a Power-plant is considered as the input to run the Vapour Absorption Refrigeration System. Aqueous Ammonia Refrigeration System is used where ammonia is used as refrigerant and water as absorbent and the heat produced by the flue gases, NH 3 changes its phase from liquid to vapour and this vapour circulates throughout the cycle and at the end, in the evaporator we get the cooling effect. In this system instead of utilizing electricity to run the system we focused to run the system by waste heat which is release from the turbine exit in the form of flue gas. By making it done its possible to release less harmful gases to the environment. Numerical calculations were conducted by varying the inlet pressure of the flue gases at the exit of the turbine. From the results it has been clearly observed that there is significant amount of increment in COP of the system. Keywords: Aqueous ammonia, Coefficient of performance (COP), Flue gas, Vapour absorption refrigeration system, Waste heat. Cite this Article: Naveen Janjanam, Sukhvinder Singh, Chandra Pavan, Raghavendra, and Lokesh Kumar. Enhancement of Refrigeration Effect using Flue Gases from Chimney, International Journal of Mechanical Engineering and Technology, 9(4), 2018, pp editor@iaeme.com

2 Naveen Janjanam, Sukhvinder Singh, Chandra Pavan, Raghavendra, and Lokesh Kumar 1. INTRODUCTION The temperature of the flue gases leaving chimney by natural draught is higher than artificial draught. As in the flue gases the heat carried out is more due to higher flue gas temperature. The gases released in the chimney are referred as flue gases which are carbon dioxide, water vapour, NO x and excess of oxygen. Generally, in industries a portion of the heat carried away by the flue gases to produce the required draught could have been used either in heating the air going to the furnace or in heating the feed water going to boiler.thus, resulting in the increase in the efficiency of installation. While considering the cases where it leads (or may lead) to the losses in the chimney are: The flow of flue gases-as there are frictional resistance offered by the flue and gas passages. Bends in the gas flow circuit. Friction head losses in grate, economizer, super-heater. Imparting velocity to the flue gases. The way by which the refrigerating effect is observed can be studied through Vapour absorption refrigeration system and are as follows Three fluid refrigeration system Aqua ammonia Electrolyte 2. LITERATURE SURVEY Principally the green house effect is a natural phenomenon. As sun light hits the earth, some of heat is reflected back in to space keeping the earth cool. While earth emits the heat energy, instead of going back out into space some part is absorbed by green house gases i.e. carbondioxide, methane, water vapour etc. When this happens the atmospheric air gets warmer and the planet as a whole gets warmer too. But at the same time it is concern to the environment if this emission rates get increased. Thus, impacting it into the effect of Global warming and causes a gradual increase in the global average air temperature at the earth s surface. Hence, considering the surrounding nature we have come to the aim to deal by not releasing the gas into the atmosphere, instead making it into useful output. The obtained gases are preferred as low grade energy i.e. waste heat from the industry is used here as the main source to run the system. 3. SYNTHESIS The flue gas losses are considerably reduced by utilizing the condensation heat which helps to lower the flue gas temperature simultaneously. And this is referred to as condensing value boilers. The circumstances to which it varies are: 1. The difference between the flue gas and combustion air is depending on temperature. 2. Flue gas concentration of CO2 or O2 is considered. 3. Fuel specific parameters are also considered. The refrigeration system uses the waste energy which is recovered from chimney in the form of flue gases. VAR System consists of ammonia as refrigerant and water as absorbent. The absorber consist the mixture of water and ammonia. The mixture then passes in to the generator. The heat is supplied to the generator using flue gases. As a result, the temperature editor@iaeme.com

3 Enhancement of Refrigeration Effect using Flue Gases from Chimney and pressure increases in the generator. The ammonia vapour formed then passes in to condenser through rectifier. While the water from generator is passed back in to absorber. Small amount of H 2 O also passes along with ammonia so in order to avoid water, a rectifier is installed prior to the generator which continuously drips off the water content and decreases the risk of stopping the choke valve and allows the water vapour to flow from the generator[7]. By using ammonia as refrigerant the system can be used for both air conditioning and refrigeration applications. 3.1 POWER PLANT LAYOUT DIAGRAM Figure 1 shows the photograph of the layout of a power plant Ammonia is one of the most punctual sorts of refrigerants which are still broadly utilized in numerous applications due to its inborn thermal properties. And therefore because of its properties it is used as the ideal refrigerant for cold storage in places like ice plants, packing plants and etc. The most commonly used refrigerant in vapour absorption systems is Ammonia for both the application in domestic as well as in industrial. It possesses the following properties. Water has large capacity to absorb ammonia vapour eg.1m³ of water at 13ºC is capable of absorbing 1000m³ of ammonia vapour. The solubility of ammonia in water at low temperature and low pressure is higher than it is at high temperature and high pressure. During absorption of ammonia vapour in water, more heat is liberated it is corrosive to metals. Water can be induced to give up dissolved ammonia by heating since the boiling temperature of ammonia is -33.3ºC at atmospheric pressure which is much lower than that of water at any pressure editor@iaeme.com

4 Naveen Janjanam, Sukhvinder Singh, Chandra Pavan, Raghavendra, and Lokesh Kumar 4. PROBLEM DEFINITION While supplying the increased energy demand, Efforts should be made to adopt measures to minimize the degradation of the environment. Thus every step must be taken to conserve the environment MOTTO In this system we utilize generator which contain NH 3 & H 2 O instead of compressor to run the AC system. As we will be supplanting compressor of AC system by generator, we spare power which has utilized to run compressor. In the present system we diminish the fuel utilization as well as this system makes a difference to diminish the exhaustion of ozone layer which primarily influence on environment NEED OF THE PROJECT To create a cooling unit, which will aid the billions of people without using electricity and also the obtained system is Eco-friendly. 5. OBJECTIVE Recover waste energy from the components and results in the refrigerating effect Save fuel which burns for working of A.C To reduce the consumption of electricity 6. COMPONENTS OF AQUEOUS AMMONIA CYCLE Figure 2 shows the aqueous ammonia refrigeration cycle Heat exchanger Evaporator Absorber Pump Generator editor@iaeme.com

5 Enhancement of Refrigeration Effect using Flue Gases from Chimney Analyzer Rectifier Condenser and expansion valve 7. PARTS AND WORKING OF AQUEOUS AMMONIA REFRIGERATION SYSTEM 7.1. Heat exchanger The heat exchanger is cooperated between the pump and the generator which cools down the weak hot solution coming from the generator to the absorber. The temperature of the strong solution leaving from the pump is raised by the heat removed from the weak solution. Now this hot strong solution goes into the analyser and generator. The operation reduces or surplus the amount of heat supplied to the generator and it cools down the solution before reentering it back to the absorber using heat exchanger Evaporator It is the component of a Refrigeration System where heat exchange takes places heat from the surrounding is absorbed i.e. (from room, cold storage, etc,) this in turn increase the temperature of refrigerant of the system. The expansion valve is used to throttle the liquid ammonia and then it evaporates by absorbing the heat in the evaporator Absorber The absorber consists of the rich solution of ammonia and water. This rich solution transfers the aqueous solution of ammonia and water into the generator. The water coming out from the generator through heat exchanger gets cooled and comes back to the generator and thus maintaining the water cycle within the system. Similarly the ammonia coming out from the evaporator which is at low pressure and low temperature re-enters into the absorber and cool down by circulating water and again becomes rich mixture in the absorber Pump Pump is used to increase the pressure of the rich solution. It circulates the rich mixture solution too Generator It is used for the distillation purpose which circulates the rich solution to the rectifier and leaves the poor solution for recycling purpose. The rich NH 3 solution is pumped to the generator where the external source is used to supply the heat (here in our case it is flue gas).since the boiling point of NH 3 is less than the boiling point of water. The NH 3 vapour is released from the aqua NH 3 solution which is at high pressure and the weak solution is again transferred to absorber through a pressure reduction channel i.e. pressure reducing valve Analyzer The main motto of the analyser is to decrease the heat input required in the generator. The analyser are used to remove the unwanted water particles before entering into the condenser, if the water particles are not made to remove then they can freeze the choke valve of the pipeline in the expansion valve. Thus this can be made as an integrated part of the generator or we can place separately and use it as equipment in the refrigeration system where it consists of stacked trays with little gap in them and are mounted above the generator. Further, editor@iaeme.com

6 Naveen Janjanam, Sukhvinder Singh, Chandra Pavan, Raghavendra, and Lokesh Kumar the strong solution from the absorber flows downward over the tray in order to cool the retiring vapours since the saturation temperature of water is higher than that of NH 3 at a given pressure, thus condensing the water vapour first. As the vapour passes upward through the analyser, it is cooled and enriched by ammonia and the liquid is heated. Thus making the vapour going to the condenser is lower in temperature and rich in NH 3 and the desized motto is obtained Rectifier The function of the rectifier is to further cool the NH 3 vapour leaving from the analyser so that there is no amount of water vapour present in the remaining NH 3 vapour i.e. should be condensed thus only allowing dry or anhydrous NH 3 vapour flows to the condenser. The drip return pipe is used to return back the condensate from rectifier. Finally, the reduction the elimination of the percentage of water takes place here Condenser and expansion valve The high pressure NH 3 vapour coming from the generator is condensed in the condenser and high pressure vapour ammonia is converted into high pressure liquid ammonia. In order to eliminate water vapour from the NH 3 vapour going into the condenser an analyser going into the condenser an analyzer rectifier combination is used. 8. PROPERTIES 8.1 Properties of ideal refrigerant It should have the properties vapour pressure characteristics that will permit boiling at 2⁰C and 10⁰C and condensation at 40⁰C or above, at pressure not far from atmospheric high critical temperature low specific heat Large latent heat of vapourization Stability in complete cycle pressure 8.2 Properties for ideal absorbent Ideal absorbent should always be in liquid condition particularly in operating conditions The absorbent should be having resemblance towards the refrigerant The discharged heat should be minimized when refrigerant is immersed into the absorbent It should posses high boiling point The specific heat should be very low It should have chemical stability 8.3 Properties for ideal refrigerant Absorbent combination The desirable absorbent refrigerant have the properties of high solubility low solubility at the condition in generator The refrigerant must be quickly evaporated at normal temperatures and when compared to absorbent they can be separated in generator The refrigerant properties should posses modest operating pressure editor@iaeme.com

7 Enhancement of Refrigeration Effect using Flue Gases from Chimney In all operating conditions the refrigerant and absorbent must be chemically stable They together should not form solid phase Absorbent should have a strong resemblance for the refrigerant They together should not cause corrosion They should exhibit the properties of non toxic and non inflammable Viscosity must be very low to assist heat and mass transfer 9. ADVANTAGES 1. It requires no power for its operation. 2. It is easy for maintenance. 3. It requires very less skill for its operation being the self activated. 4. It can be used for multi-purpose. 5. It is cheap as compared to the conventional power generation unit. 6. Waste is utilized to produce the heat. 7. The installed setup requires low high grade energy but need ample of space. 10. DESCRIPTION OF THE PROBLEM In this system there are two solutions one is saturated rich solution, and another is saturated poor solution. In saturated rich solution the liquid phase must be heated from the absorber temperature to the bubble temperature with a generator pressure. Mainly in rich solution the phase must be heated with certain temperature and pressure. While in poor solution the liquid phase must be cooled with certain absorber temperature. And when we are using these two systems, this will improve the regeneration heat exchangers between the solutions. This will reduces the amount of heat added in the generator hence increases the coefficient of performance and decrease the amount of heat rejection in the absorber. The 2 nd phase is to amplify the pressure and then examining the COP values. COP Max COP vs Pressure Pressure max cop Figure 3 shows the graphical representation of Maximum COP VS Pressure In the graph, we notice that as the pressure value increases there is also an increase in the COP values. Here, the maximum COP refers to the theoretical values which are assumed to be based on the input given to the aqueous ammonia cycle editor@iaeme.com

8 Naveen Janjanam, Sukhvinder Singh, Chandra Pavan, Raghavendra, and Lokesh Kumar Actual COP Actual COP vs Pressure Pressure in bar Act cop Figure 4 shows the graphical representation of Actual COP VS Pressure It is known that we aren t going to get the required values from the cycle due to the losses present in it. Thus this actual COP tells us the particular range of values that can be achieved after neglecting the losses. In the similar manner the COP value gets increased, while increasing the pressure but the COP obtained will always be lesser than the maximum COP expected. Actual heat Actual heat Actual heat (KJ/Sec) bar 3bar 4bar 5bar Pressure Figure 5 shows the graphical representation of Actual heat VS Pressure On varying the pressure the actual heat supplied will go down in decreasing order hence at higher pressure the initial heat given will be less and results into maximum COP at a minimum heat supplied to the system. The advantage of this is with less input, the required output can be obtained. i.e. reducing the man effects on producing heat. The comparison is made COP vs. Pressure which shows as the variation at pressure in increasing order will lead to increase in the COP values. It is important to increase the value of COP as with the minimum heat supplied to the system one can get the higher refrigerating effect as an output of it. More importantly the process is being carried out with aqueous ammonia which is eco friendly with the nature as it does not produce any harmful gases. Thus this system can be implemented in all most all the industrial plants who are seeking to at least obtain a chamber which is air cooled with the waste energy instead of using electricity editor@iaeme.com

9 Enhancement of Refrigeration Effect using Flue Gases from Chimney 11. CONCLUSION This work deals with eco friendly nature to the environment where aqueous ammonia cycle is used for the generation of refrigeration effect. Instead of using high grade energy i.e. electrical energy to generate electricity and use it for refrigeration effect, we are dealing with the waste energy released from the industry such as steam power plant where there is huge amount of flue gases released to the environment and resulting in the increase of global warming. Now these gases which are lost to environment usually have high pressure and high temperature and if concentrated further it can be improved a lot. The area approached here deals to cool a certain chamber without the use of electricity. 12. FUTURE SCOPES 1. The input to the given system can be varied based on the requirement of the plant or by altering it into higher pressure. The area which one should look forward is how they can manage to maintain the higher pressure i.e. maintaining the higher pressure itself a greater task. 2. In the society of growing technologies with respect to time there will be period where the efficiency of the power station will be more which will relates to less environmental issues and the present system will play a major role in the contribution. REFERENCES [1] Technologies To Recover Exhaust Heat From Internal Combustion Engines R. Saidur A, M.Rezaei A, W.K.Muzammil A, M.H.Hassan A, S.Paria A, M. Hasanuzzaman elseiver. [2] Sreeshankar K. K, Vikas P L, Sooraj K(2013), Vapour Absorption Refrigeration System For Cold Storage &Power Generation In Automobiles Using Exhaust Gas. [3] Khaled S. 2011, Evaluation And Performance of water- Ammonia Auto Air Conditioner System Using Exhaust Waste, Science-Direct Energy Procedia 6 (2011) [4] Subhash Kumar1, Dr.R.R Arakerimath2, Comparative Study On Performance Analysis Of Vapour Absorption Refrigeration System Using Various Refrigerants IPASJ International Journal Of Mechanical Engineering (IIJME) Volume 3, Issue 1, January 2015 Pg-07-1 [5] Works from D Y GOSWAMI [6] Flue_Gas_in_Industry_0981_2773 [2] [7] Notes from NPTEL-Version 1 ME, IIT Kharagpur editor@iaeme.com