EXPERIMENTAL ANALYSIS ONREFRIGERATION SYSTEM USING (CNT, GOLD & HAUCL4) NANO-FLUIDS aDr.S.
Sundararaj, bK.Mohan, cR.Nelsonand dD.Deepan Babu abcdDepartmentof Mechanical Engineering, Sri Krishna College of Technology, Coimbatore, TamilNadu, India. ABSTRACT:In this paper the experimentalanalysis on performance of a Vapour Compression Refrigeration System (VCRS)with Nano fluids is done.
Nano fluids are a new class of fluids which havesolid particles of 1-100 nm suspended in them. Nano-fluids along conventionalheat transfer fluids will have higher thermal conductivity. In this paper nanofluids with CNT and HAuCl4 is suspended with conventional lubricant(Polyalkylene Glycol) and the COP (Coefficient of Performance) is obtained, theamount of nanoparticles has been used in 0.1% & 0.2% vol. fraction of PAG. The COP of VCRS with CNT, Gold& HAuCl4 is calculated. The addition of Nano particles to the refrigerantresults in improvements in the thermo-physical properties and heat transfercharacteristics of the system, thereby improving the performance of therefrigeration system.
Key words: Coefficient of Performance;Vapour (COP), Compression Refrigeration System (CRS), Refrigerant; Nano fluids; INTRODUCTIONTherefrigeration system is almost found in many parts of the world for variouspurposes such as food preservation, cooling system etc. The refrigerationsystem consumes a considerable amount of power. The performance of therefrigeration system depends upon the heat transfer capacity of therefrigerant. Normally R12, R22, R600, R600a and 134a are used as a refrigerant1.
For example, the average power consumption of one-ton air-conditioner isabout 3000KW per year and for refrigerator it is about 1500KW per year 2. Nano fluid is used as a heat transfer fluidto improve the performance of the refrigeration system, one way of improvingthe coefficient of performance of the system is to increase the thermalconductivity of the refrigerant. The thermal conductivity of the fluidincreases with increase in concentration of Nano particles.
13. With the useof nanoparticles in refrigerant or lubricant, consumption of power reduces andfreezing capacity of the system increases in almost all cases. 3 With thehelp of Nano fluids the following results will occur· Increasein surface area which results in more heat transfer· Theclogging of the particle can be reduced· Byvarying the proportions of the Nano fluids the thermal conductivity can bevaried.
a) VariableCompression Refrigeration systemThe process of moving theheat from one place to other with in a controlled condition is called asrefrigeration. And moreover a reduction in the power consumption (10.87% &13.04%) along with faster cooling (from 410C – 250C) isalso achieved when nano-refrigerants are used. 6 The input to the system isgiven in the form of mechanical energy through motor to compressor. Nanoparticles (CNT, HAuCl4, and Poly Alkaline Glycol) are added to the base fluids(water, ethylene, glycol and oil) they form a new form of fluids with improvedthermal properties.b)Properties of refrigerant and Nano particles R-134a-Tetrafluoroethane(bt-260C, ?-4.
2kg/m3), CNT (k-3500 Wm-1K-1, ?-2.3g/cm3), HAuCl4 (H – 0.3%, Au -57.
9%, Cl – 41.8%, k-315 W m-1K-1, ?-3.5 g/cm3), and poly alkaline (? -1600kg/m3, flash point-497 K and pour point-228 K).
MATERIALSAND METHODSa) Experimental Method Theexperimental set up consists of a compressor, condenser, and expansion Deviceand an evaporator section here the Capillary tube is used as an expansiondevice. The evaporator is coil type which is loaded with water. Service portsare provided at the inlet of expansion device and compressor for charging therefrigerant. The mass flow rate is measured with the help of flow meter fittedin the line between expansion device and drier unit. The exergy analysis can bedone for various components • specific exergy e = ?h – T ?s• Condenser exergy (?E) =(ec x m – (1- (T/T0) )?hc xm)• Evaporator exergy (?E) = ((1-(T/T0) ?hex m – ee x m )• Capillary Tube exergy (?E) = ?s x m• Compressor exergy (?E) = ?s x m Fig. 1.
Experimental setup of VCRSb) SpecificationTable I. Specification of experimental set up S.No Components Specifications Quantity(% Vol.fraction) 1 Compressor 220v 1 2 Condenser 1 3 Evaporator 1 4 Capillary Tube 0.
5-2.28 mm diameter 1 5 Pressure gauge 0-100 psi 4 6 Temperature Sensor up to 573 K 4 7 Refrigerant R134a – 8 Nanoparticle 20-60 nm (0.1&0.2) 9 HauCl4 (Gold Nano fluid) 10ml (0.1&0.2) 10 GOLD 10ml (0.1&0.
2) 11 Energy meter 240v 1 12 Poly Alkaline Glycol 250ml – c)Preparation of Nano fluids It involvestwo steps in first step the Nano particles are produced as dry powder and inthe next step they are dispersed in a base fluid like water. The Nano fluidwill be prepared using a probe sonicator. The refrigeration system using Nano-fluidsfrom their result the COP of refrigeration system with various Nano-fluids havegreat improvements. 12Fig.2.Probe Sonicator It usesultrasonic vibrations to suspend the Nano particles (CNT, Gold and HAuCl4) inthe fraction of 0.1% & 0.
2% volume with base lubricant. The Nano fluidsincreases COP but their applications are hindered due to factors like long termstability, high pressure drop, high pumping power etc. 16 Fig.
3. Before and after sonicationd) Type and Percentage of nanoparticle and input Parameters of VCRS The experimentwill be carried out with Nano lubricant in 0.1 and 0.2% vol. fraction.
Table II. Volumefraction and quantity of nano particles S.no Type of Nano-particle %Vol. fraction Quantity 1 Gold 0.1 0.25 ml 2 Gold 0.2 0.
5 ml 3 HAuCl4 0.1 0.25m 4 HAuCl4 0.2 0.5 ml 5 CNT 0.005 25 mg The input parameters measured from the VCR TableIII.
Input parameter from VCRS S.no Parameters Range 1 Power input 622 W 2 Evaporator temperature range -15 to 15 0C 3 Voltage range 200 to 250 V 4 Motor type CSIR 5 Liquid temperature 450C 6 Compressor cooling Fan RESULTS ANDDISCUSSIONa) Time taken to cool water from 250Cto 40CThe below figure shows that the timetaken to the conventional lubricant is higher than the Nano lubricants. It isalso found that the time taken is minimum for 0.2% Gold + CNT with Lubricant. Fig. 4. Cooling Vs Concentration of Nanoparticles in LubricantThe above figure shows that the timetaken to the conventional lubricant is higher than the Nano lubricants.
It isalso found that the time taken is minimum for 0.2% Gold + CNT with Lubricant.b) Theoretical and Actual COPFig. 5. COP Vs Concentration of Nanoparticle Figure 5 shows thatthe actual COP is lesser than the theoretical COP also the actual COP is higherfor 0.1%gold + CNT when compared to the other nano particles.c) Water temperature vsActual COPFig.6.
Water temperature vs & HAuCl4Figure 6 shows that the actual COPis maximum for 0.1%HAuCl4, whereas 0.2%HAuCl4 and conventional COP are lesserin range when compared to the actual COP. Fig.7. Water temperature vs & goldIn figure 7 it is found that the actual COP is maximum for0.1%gold up to 160C and after 160C it is maximum for0.
2%gold it shows that COP value can be altered by varying the watertemperature. Fig.8. Water temperature vs & 0.2% gold + CNT In figure 8 the conventional and0.
2% gold values are same at a particular temperature (at 100C) butwhile increasing the temperature of the water the actual COP is maximum for0.2% gold. Fig.
9.Water temperature vs & 0.1% gold+ CNT In figure 9 the actual COP iscompared with the 0.1% of gold and 0.
1% of gold along with CNT it is noted thatthe mixture of 0.1% Gold + CNT attainedthe maximum COP, also their difference in range of COP between gold andconventional is large. TableIV.
Various losses in VCRS Type of lubricant Time taken to cool (s) Input power (watts) Loss in compressor (watts) Loss in condenser (watts) Loss in capillary tube (watts) Loss in evaporator (watts) Conventional 2773 89.26 0.159 0.64 0.82 0.
140 0.1% gold 2024 77.8 0.158 0.
20 0.65 0.134 0.2% gold 2099 81.02 0.173 0.39 0.
69 0.143 0.1% HAuCl4 2060 66.
9 0.169 0.36 0.75 0.089 0.
1% gold+CNT 2060 63.43 0.160 0.38 0.
64 0.121 0.2% gold + CNT 1623 92.5 0.186 0.33 0.71 0.
135 The table IV shows the Variouslosses in compressor, condenser, capillary tube and evaporator. The COP of thesystem can be increased by reducing the losses in the components (compressor,condenser, capillary tube and evaporator) different types of lubricants withdifferent proportions are added to the lubricant to improve the COP of thesystem. The power consumption of the compressor reduces by 25% when the Nanolubricant is used instead of conventional method 10.
CONCLUSIONThe addition of Nano-particles inthe VCRS has shown significant increase in the COP of the system. There is alsoa reduction in time to cool the water from higher temperature to lowertemperature. The cooling time reduction also comes with comparatively lowerheat loss in the evaporator when Nano-particles were added.
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