EXPERIMENTAL STUDIES ON SOLAR ALUMINIUM CAN AIR HEATER WITH AND WITHOUT LATENT HEAT STORAGE

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1 International Journal of Mechanical Engineering and Technology (IJMET) Volume 9, Issue 4, April 218, pp , Article ID: IJMET_9_4_17 Available online at ISSN Print: and ISSN Online: IAEME Publication Scopus Indexed EXPERIMENTAL STUDIES ON SOLAR ALUMINIUM CAN AIR HEATER WITH AND WITHOUT LATENT HEAT STORAGE G. Murali, G. Sandeep, N. Hari, M. Praveen and B. Neeraj Department of Mechanical Engineering, Koneru Lakshmaiah Education Foundation, Guntur district, Andhra Pradesh, India ABSTRACT The current paper investigates the performance studies on solar aluminium can air heater (SCAH) with and without latent heat storage. For this a solar can air heater was fabricated with recyclable aluminium cans and integrated with latent thermal heat storage (LTHS). Paraffin wax (phase changing material) was used as latent thermal storage medium. The experiments were carried out with and without LTHS system under three different mass flow rates.15 Kg/s,.22 Kg/s and.36 Kg/s. The experiments were conducted in clean days of March and April 218, Andhra Pradesh. Comparatively, the efficiency and exit air temperatures of the SCAH using latent thermal heat storage are higher than the solar can air heater without thermal storage system. The efficiency difference between SCAH with and without PCM is decreases with increase in mass flow rate. Among all three experiments SCAH with PCM produce maximum efficiency when mass flow rate was.36 Kg/s. Keywords: SCAH, PCM, Aluminium cans, Instantaneous efficiency, Latent heat. Cite this Article: G. Murali, G. Sandeep, N. Hari, M. Praveen and B. Neeraj, Experimental Studies on Solar Aluminium Can Air Heater With And Without Latent Heat Storage, International Journal of Mechanical Engineering and Technology, 9(4), 218, pp INTRODUCTION: In India there are various models of solar air heaters were developed for the purpose of space heating and food dehydration. The development of renewable energy devices such as solar air heater s facing a difficulty during absence of solar radiation. Use of latent heat storage systems in solar air heaters for effective heating of air overcoming the period of unsunshine hours. Development of a new energy storage techniques and modifications in solar air heater can reduce the miss match between supply and demand of energy[1]. Among the many ideas latent heat storage by phase change materials is suitable and feasible one. Kabeel et al [2] conducted an experiment on flat and v-corrugated SAH with and without PCM. They editor@iaeme.com

2 G. Murali, G. Sandeep, N. Hari, M. Praveen and B. Neeraj conducted experiment with different mass flow rates and also changed the thickness of PCM below flat plate collector. They found that v-corrugated SAH using PCM are giving good results when compared to that of flat plate collector. Hitesh et al [3] conducted an experimental investigation on double pass air heater with corrugated absorber plate and amul cool aluminium cans. They created a zigzag way with amul cool cans to increase thermal efficiency. They found that double pass air heater with corrugated absorber plate giving significant improvement in thermal efficiency. FilizOzgen et al [4] conducted an experiment on double flow solar air heater using aluminium cans. They performed the experiments of air mass flow rates of.3kg/s and.5 Kg/s. They done the experiments in two types, in type1 aluminium cans are arranged in zig zag manner and in type 2 aluminium cans are arranged in order. They found higher efficiency for type1 with mass flow rate.5 Kg/s. Murali et al [5, 6] used PCM in thermosyphon solar water heating system to improve the performance and further they tested spiral PCM in the water heater which gave improved performance of the water system. Sudhakar and Cheralathan[7] conducted an experimental analysis on solar energy collected by parabolic collector integrated with a sensible thermal storage unit and found that when air flow rate increases then there is a decrease in rate of heat gained because of heat loss. Aboltins et al [8] studied on a new air heating solar collector fabrication and quickly accessible materials which are used as absorbers (seed boxes made of polypropylene, black colour coated energy drink cans).they found that inflatable solar air heating collector gives good results with better efficiency. Krishnananth and KalidasaMurugavel [9] conducted an experiment analysis on double pass Solar Air Heater(SAH) with TES. They have taken Paraffin wax as thermal storage medium. They found that efficiency of SAH with TES is increased when compared to that of SAH without TES. NeelkanthGoel et al [1] investigated on design and related mathematical computations for solar air heater. They concluded that solar air heater is an efficient alternative to Electrical air heater used at residential and industrial places for long time. AbhishekSaxena and VarunGoel [11] investigated on various types of thermal energy storage used in SAH s. They found that rock bed storages are low type TES system where phase change materials are high TES system. Saxena et al [12] enhanced heat transfer rate to increase the efficiency. Granular carbon was used as heat absorbing medium in SAH. Halogen tubes (3 W) were kept inside outlet and inlet ducts. They found that thermal performances for all new configurations are better when compared to previous one. Mahmud M. Alkilani et al [13] fabricated an SAH with PCM and experimental investigation is carried out. They tested SAH by using two types of storage mediums paraffin wax and composite of paraffin wax-aluminium. They found that 7% of charging time is decreased when paraffin wax-aluminium composite is used as thermal storage. Maheshwari et al [14] experimental studies were carried on a SAH with perforated baffles in the way of airflow side of absorber plate. They found that thermal efficiency of a SAH with a baffled duct is increased by 22-33% than the SAH with a smooth duct.jiedeng et al [15] conducted experimental studies on a flat plate SAC in both cases of dust deposited surface and clean cover surface. They found that thermal efficiency in case of dust deposited surface is reduced by 1.7% - 21.% and Optical efficiency is reduced by 8.39% when the surface is covered with dust.kaushal Kishore et al [16] conducted experimental studies on a SAH with a PCM. They found that temperature at outlet of SAH is increased with that thermal efficiency is also increased. Throughout the literature survey there is no literature found regarding SCAH with and without PCM. The current paper investigates the performance studies on solar aluminium can air heater (SCAH) with and without latent heat storage. The primary aim of the study is to find the behaviour of latent heat storage on SCAH for three different mass flow rates.15 Kg/s,.22 Kg/s,.36 Kg/s and also to find suitable mass flow rate to give more performance of the solar can air heating system editor@iaeme.com

3 Experimental Studies on Solar Aluminium Can Air Heater With And Without Latent Heat Storage 2. EXPERIMENTAL SETUP Fig. 1.shows the experimental setup of SCAH with latent heat storage. The frame of solar can air heater was prepared by using plywood of 2cm thickness and coated with a matt black colour from inside and outside. To avoid the heat losses to outside bottom and all sides of solar can air heater were insulated with a foam sheets. The dimensions of solar can air heater was 12cm in length, by 6cm in width. The top solar can heater was covered with 5mm glazing glass. Instead of absorber plate recyclable aluminium cans (each 6cm diameter and 12.5cm length) were used in this project through which air is passed. Figure 1 Schematic diagram of solar aluminium can air heater experimental setup Figure 2 Photographic view of solar aluminium can air heater experimental setup For increasing the performance of system, the latent heat material (paraffin wax) was integrated with solar can air heater, 2 Kg of paraffin wax was used for the experiments and the properties of paraffin wax is given in Table.1 Paraffin wax was heated and poured into the stainless steel containers. The PCM containers which are used in the experiments is shown in Fig.3. When solar radiation falls on the collector through the transparent plate, it is absorbed aluminium cans and in turns transferred to the air circulated through the collector. So that the cold air enters through the inlet absorb the heat from aluminium can and exhausted through the outlet. A small DC fan is connected to the outlet to make the circulation inside SCAH. A editor@iaeme.com

4 G. Murali, G. Sandeep, N. Hari, M. Praveen and B. Neeraj digital anemometer was used to measure the velocity of air. Digital thermometers were used to measure the temperatures of inlet, exit, ambient & aluminium cans at different locations. To find the solar radiation intensity solar meter is used. List of instruments which were used for this study is given in Table.2. Figure 3 PCM containers used in the experiments Table 1 Properties of paraffin wax[17] S.NO PROPERTY VALUE 1 Melting temperature C 2 Latent heat of fusion 19 KJ g C 3 Thermal conductivity C 4 Solid density 876 Kg/m 3 5 Liquid density 795 Kg/m 3 6 Specific heat 2.1 KJ g C Table 2 List of instruments used for this study S.NO INSTRUMENT SPECIFICATIONS ACCURACY 1 Digital Thermometer - C to C C 2 Anemometer -3 m/s ±5% 3 Solar power meter -2 W/m 2 H at C 3. EXPERIMENTAL PROCEDURE AND THERMAL PERFORMANCE CALCULATION Experiments were carried on solar can air heater for three various mass flow rates without and with latent thermal storage system. The readings of solar power meter, digital thermometer, digital anemometer reading was taken for every one hour from 9 AM to 5 PM during the experiment at, adepalle, Andhra Pradesh, India. For each mass flow rate, the readings were taken for three days and similar readings are compared. The energy gained by the air across the heater is given by; T o -T i (1) where m is the mass flow rate of air(kg/s), C p is the specific heat of the air g C o is temperature of air leaving C and T i is the temperature of air entering C. Instantaneous thermal efficiency of the collector is defined as the ratio between the energy gain and the solar radiation incident on the collector plate, A c (2) where Q is energy gained by air (J/s), I is solar radiation(w/m 2 ), A c is collector area (m 2 ). The daily efficiency of collector is defined by accumulative heat gained by the air to the cumulative solar radiation incident on the collector surface through the day editor@iaeme.com

5 9.AM 1.AM 11.AM 12.PM 1.PM 2.PM 3.PM 4.PM 5.PM 9.AM 1.AM 11.AM 12.PM 1.PM 2.PM 3.PM 4.PM 5.PM Experimental Studies on Solar Aluminium Can Air Heater With And Without Latent Heat Storage 4. RESULTS AND DISCUSSION The thermal performance of the SCAH with and without PCM was investigated for three different mass flow rates of.15kg/s,.22kg/s,.36kg/s. Firstly the SCAH was experimented with PCM when the mass flow rates are.15kg/s,.22kg/s,.36kg/s on consecutive clean days of March and April 218. Fig.4 shows the hourly temperature variations of the different measured elements of SCAH with PCM on 24/3/218 when m=.15 Kg/s. It shows that the temperature of elements increases with the time and reaches maximum at 1:3 PM. The max measured values of T c, T, T o were found to e C respectively and maximum global radiation was 97.8 W/m 2.The ambient temperature varies between to C ig shows the hourly temperature variations of the different measured elements of SCAH without PCM on 25/3/218 when m=.15 Kg/s. The maximum measured values of T c, T, T o were found to e C and axi u glo al radiation was 947 W/m 2 he a ient te perature varies etween to C Figure 4 Temperature variations of different elements of SCAH with PCM vs time for m=.15kg/s Figure 5 Temperature variations of different elements of SCAH without PCM vs time for m=.15kg/s editor@iaeme.com

6 9.AM 1.AM 11.AM 12.PM 1.PM 2.PM 3.PM 4.PM 5.PM 9.AM 1.AM 11.AM 12.PM 1.PM 2.PM 3.PM 4.PM 5.PM G. Murali, G. Sandeep, N. Hari, M. Praveen and B. Neeraj Fig.6 shows the hourly temperature variations of the different measured elements of SCAH with PCM on 22/3/218 when m=.22 Kg/s. It shows that the temperature of elements increases with the time and reaches maximum at 1:3 PM. The max measured values of T c, T, T o were found to e C respectively and axi u glo al radiation was W/m 2 he a ient te perature varies etween to C Fig.7 shows the hourly temperature variations of the different measured elements of SCAH without PCM on 21/3/218 when m=.22 Kg/s. The maximum measured values of T c, T, T o were found to e C and axi u glo al radiation was 2 he a ient te perature varies etween to C Figure 6 Temperature variations of different elements of SCAH with PCM vs time for m=.22kg/s Figure 7 Temperature variations of different elements of SCAH without PCM vs time for m=.22kg/s 15 editor@iaeme.com

7 9.AM 1.AM 11.AM 12.PM 1.PM 2.PM 3.PM 4.PM 5.PM 9.AM 1.AM 11.AM 12.PM 1.PM 2.PM 3.PM 4.PM 5.PM Experimental Studies on Solar Aluminium Can Air Heater With And Without Latent Heat Storage Fig.8 shows the hourly temperature variations of the different measured elements of SCAH with PCM on 23/3/218 when m=.36 Kg/s. It shows that the temperature of elements increases with the time and reaches maximum at 1:3 PM. The maximum measured values of T c, T, T o were found to e C respectively and axi u glo al radiation was W/m 2.The ambient temperature varies between 32.3 to 4 C. Fig.9 shows the hourly temperature variations of the different measured elements of SCAH without PCM on 1/4/218 when m=.36 Kg/s. The max measured values of T c, T, T o were found to e 2 C and axi u glo al radiation was he a ient te perature varies etween to C Figure 8 Temperature variations of different elements of SCAH with PCM vs time for m=.36kg/s Figure 9 Temperature variations of different elements of SCAH without PCM vs time for m=.36kg/s Fig.1 shows that the global solar radiation on the date of experiments for both SCAH with and without PCM when mass flow rates of.15 Kg/s,.22 Kg/s and.36 Kg/s. It is clear from figure that the radiation intensity was almost similar for all consecutive days of the experiments during March and April 218. For this particular condition experiment data was editor@iaeme.com

8 9.AM 1.AM 11.AM 12.PM 1.PM 2.PM 3.PM 4.PM 5.PM Instantaneous Efficiency 9.AM 1.AM 11.AM 12.PM 1.PM 2.PM 3.PM 4.PM 5.PM G. Murali, G. Sandeep, N. Hari, M. Praveen and B. Neeraj collected for number of days. The data selected for discussion was based on similar solar intensity pattern for concurrent results I( W/m2 )on I( W/m2 )on I( W/m2 )on I( W/m2 )on I( W/m2 )on I( W/m2 )on Figure 1 comparison of solar radiation on different days of experiment vs time From fig.11 it is clear that SCAH with PCM gave 44% efficiency improvement than without PCM when mass flow rate.15 Kg/s. The efficiency is increased with respect to time and it reaches its maximum value 77% at the time of 2PM m=.15 Kg/s Time of Day m=.15kg/s with PCM.15Kg/s without PCM Figure 11 comparison of instantaneous efficiency with and without PCM vs Time From fig.12 it is clear that SCAH with PCM gave 31% efficiency improvement than without PCM when mass flow rate.15 Kg/s. The efficiency is increased with respect to time and it reaches its maximum value 7% at the time of 5PM editor@iaeme.com

9 9.AM 1.AM 11.AM 12.PM 1.PM 2.PM 3.PM 4.PM 5.PM 9.AM 1.AM 11.AM 12.PM 1.PM 2.PM 3.PM 4.PM 5.PM Instantaneous Efficiency Experimental Studies on Solar Aluminium Can Air Heater With And Without Latent Heat Storage m=.22 Kg/s Time of Day m=.22kg/s with PCM m=.22kg/s without PCM Figure 12 comparison of instantaneous efficiency with and without PCM vs Time From Fig.13 it is clear that SCAH with PCM gave 16% efficiency improvement than without PCM when mass flow rate.15 Kg/s. The efficiency is increased with respect to time and it reaches its maximum value 89% at the time of 2PM. The efficiency difference between SCAH with and without PCM is decreases with increase in mass flow rate. Fig.14 shows among all three experiments SCAH with PCM produce maximum efficiency when mass flow rate was.36 Kg/s. It may best suited mass flow rate for SCAH with PCM m=.36 Kg/s Time of Day m=.36kg/s without PCM m=.36kg/s with PCM Figure 13 comparison of instantaneous efficiency with and without PCM vs Time

10 9.AM 1.AM 11.AM 12.PM 1.PM 2.PM 3.PM 4.PM 5.PM Instantaneous efficiency G. Murali, G. Sandeep, N. Hari, M. Praveen and B. Neeraj Time of Day m=.15kg/s with PCM.15Kg/s without PCM m=.22kg/s with PCM m=.22kg/s without PCM m=.36kg/s without PCM m=.36kg/s with PCM Figure 14 Comparison of instantaneous efficiency for different mass flow rates with and without PCM vs time 5. CONCLUSION The SCAH integrated with PCM containers as latent heat storage medium was studied experimentally when mass flow rates were.15 Kg/s,.22 Kg/s and.36 Kg/s. The instantaneous thermal efficiency of SCAH was studied with and without PCM for three different flow rates. The instantaneous efficiency is higher in case of heater with PCM generally. The instantaneous efficiency of SCAH with PCM was 44% improved than without PCM when mass flow rate was.15 Kg/s, in the same way 31% improvement in efficiency was obtained for SCAH with PCM when mass flow rate was.22 Kg/s and 16% improvement in efficiency when mass flow rate was.36 Kg/s than the corresponding ones without using PCM. The efficiency difference between SCAH with and without PCM is decreases with increase in mass flow rate. However lower the mass flow rate higher the efficiency improvement, Among all three experiments SCAH with PCM produce maximum efficiency when mass flow rate was.36 Kg/s. It may best suited mass flow rate for SCAH with PCM. NOMENCLATURE T c1 = can temperature C A c = collector area (m 2 ) T c2 = can te perature C ŋ = thermal efficiency(%) T i = inlet te perature C C p = specific heat of air at constant pressure (kj/kg K) T o = outlet te perature C m = mass flow rate of air(kg/s) T = inside air te perature C I = solar radiation (W/m 2 ) T c = average can te perature C REFERENCES [1] Bhushan B, Singh R A review on methodology of artificial roughness used in duct of solar air heaters Energy35, 21: [2] A.E.Kabeel, A.Khalil, S.M.Shalaby, M.E.Zayed, Experimental investigation of thermal performance of flat and v-corrugated plate solar air heaters with and without PCM as thermal energy storage Energy conversion and Management 113, 216,PP no: editor@iaeme.com

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