Experimental Investigation of Heat Exchanger Performance by Using Phase Change Material With Aluminium and Copper Micro Particles

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Experimental Investigation of Heat Exchanger Performance by Using Phase Change Material with Aluminium and Copper Micro Particles

A. Muhammed Shihan1, J. Chandra Dass2, TTM. Kannan3

1Full-time Research Scholar, 2Asst. Professor, 3Associate Professor Dept of Mechanical Engineering, PRIST University, Thanjavur, India

International Journal of Research in Mechanical Engineering

Volume 3, Issue 1, January-February, 2015, pp. 08-15 ISSN Online: 2347-5188 Print: 2347-8772, DOA : 24012015

IASTER 2014, www.iaster.com ABSTRACT Low Temperature Energy Storage System (LTESS) stores the thermal energy from solar, exhaust gases and waste heat from industries. To achieve this energy storage, the medium adopted is Phase Change Materials (PCM). PCM is preferred because of their higher storage density, with less volume. The disadvantage of PCM for using as LTESS is that, the thermal conductivity of PCM is less and this requires more time period and surface area of contact, for loading and unloading of thermal energy. To overcome this problem, an attempt was made to incorporate CU Micro particles in the paraffin PCM to improve its thermal conductivity. The thermal conductivity of LTESS is determined both analytically and experimentally. Incorporating micro-particle in the PCM has improved the thermal conductivity of the LTESS. Maxwell-Garnett Equation is used to determine the thermal conductivity of PCM analytically and Transient Hot Wire Thermal Conductivity Measuring Apparatus KD2 probe is used to determine the thermal conductivity experimentally.

Keywords: Low Temperature Energy Storage system, Thermal Energy Storage, Phase Change Materials, Micro materials. 1. INTRODUCTION Phase Change Materials (PCMs) are very important for thermal protection and optimal utilization of energy. It is one of the most efficient ways of storing thermal energy. It provides much higher storage density, with a smaller temperature difference between storing and releasing heat. Furthermore, there are a lot of phase change materials that melt and solidify at a wide range of temperatures, making them attractive in a number of applications. An overview of phase change materials (PCMs) used in low thermal energy systems has been by Abhat (1983), Zalba et al. (2003) and Farid et al. (2004). The ideal phase change material to be used for latent heat storage as known must meet following requirements: high sensitive heat capacity and heat of fusion; stable stochiometric composition; high density and heat conductivity; chemical inert; non-toxic and non-inflammable; reasonable and inexpensive. The various PCMs are generally divided into two main groups: organic and inorganic compounds. Organic compounds present several advantages like ability of congruently melting, self-nucleating properties, non-corrosive behavior and compatibility with conventional materials of construction. Sub-groups of organic compounds include paraffin and non-paraffin organics. Technical grade paraffins have been extensively used as heat storage materials due to wide melting/solidification temperatures ranges and have a relatively high latent heat capacity. They have also no sub cooling effects during the

International Journal of Research in Mechanical Engineering Volume-3, Issue-1, January-February, 2015, www.iaster.com ISSN

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solidification as well as a small volume change during the phase change processes. They are chemically stable, non-toxic and non-corrosive over an extended storage period. Widely used non-paraffin organics, as heat storage materials, are fatty acids like lauric, myristic, palmitic and stearic acid. Their advantages are a possibility for reproducible melting and solidification behavior and little or no sub cooling effects. Low thermal conductivity is the main disadvantages of all organic compounds. The main advantages of inorganic compounds are a high volumetric latent heat storage capacity, often twice the capacity of organic compounds, and high thermal conductivity. Salt hydrates are frequently used inorganic compounds. Their disadvantages include incongruent melting. Paraffin waxes are cheap with moderate thermal storage density and a wide range of melting temperature. However, searching on a material that have a large latent heat, high thermal conductivity, melt congruently with minimum sub-cooling, chemically stable, low in cost, non-corrosive has attracted great interest in research around the world. 2. LITERATURE SURVEY The majority of the literature research on the LHTES system has been performed for shell and tube arrangement, and more recently for spherical shells. Saitoh and hirose performed a theoretical and experimental investigation of transient thermal characteristics of a phase change thermal energy storage unit using spherical capsules Takayuki watanable et al. developed a numerical model for prediction of the transient behavior of the latent heat storage module. The model is one-dimensional with a finite overall heat transfer co-efficient between the PCM and the Heat Transfer Fluid (HTF). They conducted the experiments on the heat storage module consisted of PCM (paraffin wax) with different melting temperatures using water as HTF both the experimental and numerical results showed some improvements in charging and discharging rates by use of the three-types PCM.J.L.Zeng, L.X.Sun, F.Xu, Z.C.Tan, Z.H.Zhang, J.Zhang and T.Zhang studied an experimental and theoretical investigation of a PCM based energy storage system containing Ag nano particles. In this paper, organic phase change material (PCM)/Ag nanoparticles composite materials were prepared and characterized for the first time. The effect of Ag nanoparticles on the thermal conductivity of PCM was investigated. This experiment results indicated that the Ag nanoparticles dispersed uniformly in the materials, occurred in the forms of pure metal.F.Frusteri, V.Leonardi, S.Vasta, G.Restuccia was measured a thermal conductivity of a PCM based energy storage system containing carbon fibers. In this paper, the thermal conductivity enhancement of PCM44, an eutectic mixture of Mg (NO3)26H2O-MgCl26H2O-NH4NO3, using carbon fibers has been investigated. Moreover, a numeric heat transfer model to describe the change of the thermal conductivity of PCM as a function of fiber content is proposed. M.N.A.Hawlader, M.S.Uddin, MyaMyaKhin performed a microencapsulation of PCM thermal energy storage system. In the present study, microencapsulation of a PCM was carried out by two different methods, namely complex coacervation and spray drying, and a comparison of the characteristic properties of the products was made. Ronny Hentra, Hamdani, T.M.I.Mahila, H.H.Masjuki presented the thermal and melting heat transfer characteristics in a latent heat storage system using micro. This paper focuses mainly on the study of charging process in the system, and includes the following aspects: (i) Experimental study for thermal analysis of the heat storage system, (ii) experimental and formulation of the physical properties of the PCM micro, (iii) a theoretical model for thermal analysis of the melting process, (iv) validation of the theoretical results with experimental data and theoretical establishment of the phase change behavior during melting. Yuichi Hamada, Jun Fukai was investigated the effect of the carbon fiber brushes on the thermal outputs of practical scale LHTES tanks, which are installed in an air conditioning system of a building as a resource for space heating. The experimental investigation using practical scale equipment is limited because the operating conditions are not arbitrarily established, contrary to the case when using laboratory scale equipment. Accordingly, the thermal outputs calculated using the previously reported three dimensional heat transfer model are compared with the experimental ones. The effect of


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the carbon fiber brushes on the thermal outputs of the tanks is then numerically discussed. Anica Trp analyzed the latent thermal energy storage system is a shell-and-tube type of heat exchanger with PCM filling the shell side. The results of experimental investigations on PCM thermal characteristics during melting and solidification process in a vertical two concentric pipe energy storage system have been presented by many authors. Hassan (1994) studied thermal energy storage system employing palmitic acid. Dimaano and watanable (2001) investigated latent heat storage system with capric and lauric acid mixture. Sarri and Kaygusuz (2001) studied thermal energy storage system using stearic acid and the same authors (2002) investigated thermal characteristics of eutectic mixture of lauric and stearic acids. Sari (2003) studied the thermal energy storage system using an eutectic mixture of myristic and palmitic acids. All of these authors have obtained similar shapes of PCM temperature profiles during melting and solidification and described the governing mechanisms of heat transfer in the distinct segments of the processes. Heat transfer in this type of thermal energy storage system represents a transient conjugate phase change forced convection problem. Bellecci and conti (1993) using the enthalpy method, studied numerically the cyclic behavior of a phase change solar shell and tube energy storage system. Ismail and Goncalves (1999) analyzed phase change heat transfer around a tube immersed in the PCM, with assumption of a constant heat transfer co-efficient between working fluid and the wall. Cao and Faghri (1991, 1992) numerically stimulate the transient behavior of the shell-and-tube thermal energy storage system with a HTF of low prandtl number. For the phase change heat transfer, the temperature transforming model was used. Zhang and Fagri (1996) semi-analytically studied a shell-and-tube latent thermal energy storage system with a HTF of moderate prandtl number. They concluded that the laminal forced convective heat transfer inside the tube never reaches the fully developed state and that it must be solved simultaneously with the phase change of the PCM. Accordingly numerical calculations of transient heat transfer in the shell- and-tube latent heat storage system with HTF of moderate prandtl number require the application of CFD methods. R. Velraj, A. Pasupathy to provide a compilation of much of practical information on different PCMs and systems developed for thermal management in residential and commercial establishments followed by existing systems in use and possible future directions based on latent heat storage technology in building integrated energy system. Brend Hafner, Klemens Schwarzer, Ginsterweg, was improved the heat transfer in a phase change-material storage. The aim of this project Latent Heat Storage, financed by the German ministry BMBF (NO. a700297), was the development of a latent heat storage based on paraffin. Two different approaches were investigated in the project: (i) short term PCM storage, based on conventional water storage and equipped with latent heat elements. (ii) A long term storage using a separate volume as PCM storage. 3. EXPERIMENTAL DETAILS

Fig 1 Experimental Setup


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The experimental apparatus was composed of a test unit, two constant temperature water containers set at different temperatures (above and below the melting/solidification temperature of the PCM) and pumps supplying water from the constant temperature containers to the test unit. Preceding the experiments, the PCM tube was filled with the paraffin wax. Melting experiments started at room temperature and the paraffin wax was in the solid phase. Initial conditions for melting were established by the circulating water from the low temperature container at environmental temperature. Initial conditions were established when all thermocouples inside the paraffin wax were recording the same temperature. Cold water was then quickly drained from the HTF (Heat Transfer Fluid) tube. Water from the hot temperature container at a required temperature, over the melting range, started to circulate and data collection began. The mass flow rate of the water was constant. Temperature data for all thermocouples were collected every 10s. When all measured PCM temperatures were above the melting temperature range and when they reached the same temperature (slightly below the water temperature in the HTF tube), the melting experiment was finished. The solidification experiment was then started with established initial conditions. Hot water was drained from the HTF tube and water from the cold temperature container, with a constant mass flow rate and temperature below the solidification temperature range, started to circulate. Temperature distributions in the PCM were measured and recorded at the same time interval as in the melting experiment. A solidification experiment was completed when all thermocouples within the paraffin had reached the same temperature.

4. RESULT AND DISCUSSION 4.1 Aluminium with Paraffin Wax

Table 1Thermal Conductivity of Aluminium Particle with Paraffin Wax

S.no Temp of hot fluid,

C

Temp of cold

fluid, C

Mass flow rate of

hot fluid, (mh)

Mass flow rate of cold fluid, (mc)

Heat transfer rate, (Q)

Heat transfer co-efficient, (U)

Logarithmic mean

temperature Difference

(T lm) 0. Thi Tho Tci Tco (Kg/s) (kg/s) K watts W /m2 K K

1. 65 60 35 42 0.01667 0.01667 0.47878 0.51083 23.49

2. 70 65 34 46 0.0200 0.0200 0.71179 1.877 10.864

3. 72 67 34 48 0.0250 0.0250 0.9944 1.9596 13.169

4. 73 69 35 50 0.0300 0.0300 1.1932 2.1016 27.410

5. 76 71 33 52 0.04002 0.04002 2.009 2.5280 29.380 4.1 Calculation

1.Total heat transfer rate in the heat exchanger, (Q) Q = {{mhCph (Thi Tho)} + {mcCpc (Tci Tco)}} / 2 = [0.01667 x 4.187 (65-60) + 0.01667 x 4.187 x(42-35)] / 2 = 0.41878 KW

Logarithmic mean temperature difference, (Tlm) Tlm = (T2 - T1) / lm (T2/T1) T1 = (Thi Tci)= 65 - 35 = 30C T2 = (Tho Tco) = 60 42 =18C Tlm= 23.49 K


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Overall heat transfer co-efficient (u) U = Q / A Tln A = D L A = (Di -do) x L A = (0.0375 0.0128) x 0.45 A = 0.0349m2 U = 0.41878 / (0.0349 x 23.49) U = 0.51083KW Q = {{mhCph (Thi Tho)} + {mcCpc (Tci Tco)}} / 2 = (0.020 x 4.187 (70-65) + (0.20 x 4.187(46-34) / 2 = [0.4187 + 1.0048] / 2 = 0.71179 KW Tlm = (T2 - T1) / lm (T2/T1) T1 = (Thi Tci) = 70 - 34 = 34C T2 = (Tho Tco) = 65 - 46 =19C Tlm= 10.8643 K Overall heat transfer co-efficient (u) U = Q / A Tln A = D L A = (Di -do) x L A = (0.0375 0.0128) x 0.45 A = 0.0349m2 U = 0.71179 / (0.0349 x 10.8643) U = 1.877KW

1. Q = {{mhCph (Thi Tho)} + {mcCpc (Tci Tco)}} / 2 = [0.025 x 4.187 (72 67) + 0.025 x 4.187 (48 x 34) / 2 = (0.523375 + 1.46545) / 2 = 0.9944 KW Tlm = (T2 - T1) / lm (T2/T1) T1 = (Thi Tci) = 72 - 34 = 38C T2 = (Tho Tco) = 67 48 =17C Tlm= 13.169K Overall heat transfer co-efficient (u) U = Q / A Tln U = 0.9944 / (0.0349 x 13.169) U = 1.9596 KW

2. Q = {{mhCph (Thi Tho)} + {mcCpc (Tci Tco)}} / 2 = [0.030 x 4.187 (73-69) + 0.03 x 4.187 (50-35)] / 2 = (0.50244 + 1.88415) / 2 = 1.1932KW Tlm = (T2 - T1) / lm (T2/T1) T1 = (Thi Tci) = 73 - 35 = 38C T2 = (Tho Tco) = 69 50 =19C Tlm= 27.411 K


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Overall heat transfer co-efficient (u) U = Q / A Tln U = 1..1932 / (0.0349 x 27.411) U = 2.1016 KW

3. Q = {{mhCph (Thi Tho)} + {mcCpc (Tci Tco)}} / 2 = [( 0.04 x 4.187 (76 71) + 0.04 x 4.187 (46 34)] / 2 = [0.8374 + 3.18212] / 2 = 2.0097 KW 4.2 Analytical Method of Copper Maxwell Garnet Equation is used to determine the thermal conductivity of PCM for LTES. The

Maxwell Garnet Equations is kMaxwell= p + 2k1 + 2( p + k1) } k1 / { p + 2k1 + 2( p + k1) }c Where kp is the thermal conductivity of the dispersed particles. Thermal conductivity of copper = 385 W/mK. kl is thermal conductivity of the dispersion liquid, Thermal conductivity of paraffin wax = 0.214 W/mK. is the particle volume concentration of the suspension. 4.3 Copper with Paraffin Wax

Table 3.Thermal Conductivity of Aluminium Particle With Paraffin Wax

S.no

Temp of hot

fluid, C

Temp of cold

fluid, C

Mass flow rate of

hot fluid, (mh)

Mass flow rate of

cold fluid, (mc)

Heat transfer

rate, (Q)

Heat transfer co-

efficient, (U)

Logarithmic mean

temperature Difference (T lm)

0. Thi Tho Tci Tco (Kg/s) (kg/s) K watts W /m2 K K

1. 65 59 35 43 0.01667 0.01667 0.4885 0.6280 22.27

2. 68 61 34 46 0.02012 0.02012 0.8361 1.0318 23.21

3. 71 63 34 51 0.03201 0.03201 1.675 2.1621 22.20

4. 75 70 33 55 0.03521 0.03521 1.990 2.17465 24.62

5. 78 72 34 60 0.04101 0.04101 2.747 3.1962 26.22

Calculation

1. Q = {{mhCph (Thi Tho)} + {mcCpc (Tci Tco)}} / 2 =[( 0.01667 x 4.187 (65 59) + 0.1667 x 4.187 (43 35)] / 2 =0.48857 KW Tlm = (T2 - T1) / lm (T2/T1) = (Thi Tci) = 65 - 35 = 30C = (Tho Tco) = 59 43 =16C = 22.27C


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2. Q = {{mhCph (Thi Tho)} + {mcCpc (Tci Tco)}} / 2 = [(0.02102 x 4.187 (68-61) + (0.02102 x 4.187 (46-34)]/2 = [0.616075 + 1.056128] / 2 = 0.83610 KW Tlm = (T2 - T1) / lm (T2/T1) = (Thi Tci) = 68 - 34 = 34C = (Tho Tco) = 61 46 =15C = 23.218 K

Overall heat transfer co-efficient (u) U = Q / A Tln U = 0.83610 / (0.0349 x 23.218) U = 1.031807 3. Q = {{mhCph (Thi Tho)} + {mcCpc (Tci Tco)}} / 2 = [0.03201 x 4.187 (71-63) + 0.0321 x 4.187 (51-34)] / 2 = [1.0722069 + 2.278439] / 2 = 1.67532KW Tlm = (T2 - T1) / lm (T2/T1) = (Thi Tci) = 71 - 34 = 37C = (Tho Tco) = 63 51 =12C = 22.2022 K U = Q / A Tln = 1.67532 / (0.0349 x 22.2022) = 2.16210KW Tlm = (T2 - T1) / lm (T2/T1) = (Thi Tci) = 75 - 33 = 42C = (Tho Tco) = 70 55 =15C = 26.2232 K Overall heat transfer co-efficient (u) U = Q / A Tln = 1.99022 / (0.0349 x 26.2232) = 2.17465KW 3.Q = {{mhCph (Thi Tho)} + {mcCpc (Tci Tco)}} / 2 = [0.04101 x 4.187 (78-72) + (0.0.4101 x 4.187 (60-34)] / 2 = [1.030253 + 4.46443] / 2 = 2.7473 KW Tlm = (T2 - T1) / lm (T2/T1) = (Thi Tci) = 78 - 34 = 44C = (Tho Tco) = 72 60 =12C = 24.6288 K Overall heat transfer co-efficient (u) U = Q / A Tln = 2.7473 / (0.0349 x 24.6288) = 3.19622 KW


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5. CONCLUSION Initially we can see that the thermal conductivity of paraffin wax is 0.214W/MK and analytically it is increased to 0.2697W/MK with the addition of aluminum micro particles and experimentally it is increased to 0.3102W/MK. At volume of 0 the thermal conductivity remains same i.e. thermal conductivity of paraffin wax is 0.214 W/MK. When the volume concentration increases to 0.02, the thermal conductivity also increases to 0.242W/MK. The micro particles we employed is the reason for the thermal conductivity improvement. This method is efficient to enhance the thermal conductivity of organic PCM. Further the experiment is tested in various nano particles like copper and magnesium in the same heat exchanger. It will be compared based on the performance in various conditions. REFERENCES [1] B. Zalba, J.M.Marin, L.F.Cabeza, H.Mehling, Review on thermal energy storage with phase

change materials heat transfer analysis and applications, Applications of Thermal Engineering 23 (2003) 251-283.

[2] C.Vaccarino, F.Frusteri, A.Barcaccia, G.Galli, G.Maisano, Low Temperature Latent Heat Storage System Utilizing Mixtures of Magnesium Salt Hydrates and Ammonia Nitrate, J.solar Energy Engineering 107 (1985) 54.

[3] Tomlinson, J. Solar Thermal Energy Storage in Phase Change Materials. American Solar Energy Society Annual Conference, Coca Beach, FL, 15-18 June, 1992.pp.174-9.

[4] Eftekhar, J., Hajji -Sheikh, A., and Lou, D., 1984, Heat Transfer Enhancement in a Paraffin Wax Thermal Energy Storage System,ASME J. sol. Energy Eng., 106. Pp. 299-306.

[5] A. Hassan, Thermal Energy Storage System with Stearic Acid as Phase Change Material, Energy Covers. Manage. 35 (10) (1994) 843-856.

[6] Sari A. (2003a) Thermal Characteristics of a Eutectic Mixture of Myristic and Palm Tic Acids as Phase Change Material for Heating Application, Appl. Thermal Eng. 23(8), 1005-1017.

[7] Hasnain SM. Review on Sustainable Thermal Energy Storage Technologies, Energy Converts Manage 1998:39:1127-38.

[8] Abhat A. Low-temperature Latent Heat Thermal Storage: Heat Storage Materials. Solar energy 1983; 30(4):313-32.

[9] Feldman, D., Shapiro, M.M and Banu, D.(1986). Organic Phase Change Materials for Thermal Energy Storage , Solar Energy Materials, 13(1),1-10.

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Experimental Investigation of Heat Exchanger Performance by Using Phase Change Material With Aluminium and Copper Micro Particles