DESIGN AND FABRICATION OF THERMOELECTRIC COOLER CUM HEATER

Transcription

1 Volume 118 No , ISSN: (printed version); ISSN: (on-line version) url: ijpam.eu DESIGN AND FABRICATION OF THERMOELECTRIC COOLER CUM HEATER B.Selva Babu 1, Jithin Raj M 2, Jobin Mathew 3, Midhun Jacob 4. selvababu@avit.ac.in 1 Department of Mechanical Engineering., Aarupadai Veedu Institute of technology 2 Principal, AVIT College 2-4 UG Students,Department of Mechanical Engineering, Aarupadai Veedu Institute of Technology. KEYWORDS:- THERMOELECTRIC COOLER, REFIREGRATION AND FLUIDS ===================================================================== ABSTRACT It is the idea of producing a cooling and heating effect in one single chamber that shifts from its maximum temperature to its minimum temperature just by adjusting a simply operated switching button.this type of a device can find wide variety of application in medicinal, food and beverage transportation commercially and also for house hold purposes. Travelers can make the best use of it. This can work either with solar power or rechargeable batteries. Design and Fabrication done on Thermoelectric cooler cum heater. ===================================================================== 1.INTRODUCTION Based on the working principle refrigeration principle, refrigeration system can be classified as vapour compression systems, vapour absorption systems, gas cycle systems etc. In 90% of applications in the world, vapour compression system is used. Air cycle and vapor absorption refrigeration covers 5% and is covered using systems like thermoelectric, magnetic, gas cycle, acoustic and other refrigeration methods. In recent years, with the increase of the awareness towards environmental degradation due to the production, use and disposal of heat carrier (CFCs and HCFCs) fluids is conventional refrigeration systems has become a subject of great concern. The major hazards to the environments are stratospheric ozone layer depletion and the greenhouse effect due to the presence of CFCs and HCFCs in the troposphere. Besides, these kinds of refrigeration systems having limitation of use of grid power and same cannot be utilized for remote application. Due to the advancement of technology and science there are a lot of practical application which require the functions of both refrigerator and heater, that is cooling and heating. Here, we demonstrate a novel refrigerator cum heater which works on the principle of therrmoelectric effect. Being driven by thermoelectric holds a lot of advantages like elimination of mechanical components, light in weight, noise and vibrationless operation, precise temperature 935

2 control etc.. in spite of its lower COP compared to widely used vapour compression systems. 2. PRINCIPLE Thermoelectric systems are solid-state heat devices that either convert heat directly into electricity or transform electric power into thermal power for heating or cooling, such devices are based on electric effects involving interactions between the now of heat and electricity through solid bodies. A discussion of thermoelectric effects and devices should start with the most fundamental phenomena. the Seebeck effect or thermo power. In the early 1800s, Seebeck observed that if two dissimilar materials were joined together and the junctions were held at different temperatures a voltage difference was developed that was proportional to the temperature difference.the ratio of the voltage developed to the temperature gradient is related to an intrinsic property of the materials called the Seebeck coefficient or the thermo power. The Seebeck coefficient is very low for metals and much larger for Semiconductors. A related effect( Peltier ettect) was discovered a few years later by Peltier, who observed that if an electrical current passed through the junction of two dissimilar materials, heat is either absorbed or rejected at the junction depending direction of the current. Two objects are considered to be in thermal equilibrium if the exchange of heat does not exist when they both are placed in contact. This fact, objects in the same temperature are said to be in thermal. This is called zeroth law of thermodynamics. Two objects at different placed in contact exchange energy in an attempt to establish thermal. Any work done during this process is the difference of heat lost by an object and won by not object. This is the first law of thermodynamics, in other words, energy are always conserved. 3. DESIGN The basic problem, apart from selection of components, we were faced during the design phase was the selection of proper switching mechanism between the working 936

3 modes that is cooling and heating, according to user's selection The options were mechanical switching and micrometer switching, Due to less complexity and additional features, we selected microcontroller switching system with two relays. The final design we reached after Discussions and opinions is shown here. 4. REQUREMENTS, SELECTION AND SPECIFICATIONS The hardware requirement or the is listed and the selection criteria were planned. The fully reversible. Changing the polarity of the DC power supply causes heat to be pumped in the opposite direction A cooler can then become a heater. Fig 3.1 Design of the system suitable components considering various factors are selected The major hardware requirements of the system are listed below: Thermoelectric Module (TEM) Refrigerating cabin Insulation Battery Cooling fan and heat sink Microcontroller Temperature sensor Display panel Temperature input unit Fig 4.1: Flow chart of module selection 5. WORKING Thermoelectric refrigeration replaces the three main working parts with a cold junction, a heat sink and a DC power source. The refrigerant in both liquid and vapour form is replaced by two dissimilar conductors. The cold junction (evaporator 937

4 surface) become scold through absorption of energy by the electrons as they pass from one semiconductor to another instead of energy absorption by the refrigerant as it changes from liquid to vapour. The compressor is replaced by a DC power source which pumps the electrons from one semiconductor to another. From the battery the power is delivered to Peltier modules connected in parallel each attached to their respective heat sinks. used for mounting: Mechanical mounting A thermoelectric module is placed between two heat exchangers (plates) fixed by screws or bolts Adhesive bonding 6. EXPERIMENTAL SETUP A bottle of water is taken and placed inside the aluminium cabin. The cabin is kept open for some times to pass air to cabin. The temperature sensor is placed inside the bottle dip in the water to measure the temperature of water. Now, using the system the water is cooled from 31 c to 24 c and the time taken for it is noted. Next, the system in heating mode, the water is brought to 31 c from 24 c. 7. FABRICATION For getting perfect insulation, a cool box having thermocol insulation and gaskets is selected. 7.1 TEM MOUNTING The efficiency of thermoelectric module assembly as a whole depends on the quality mounting an object to be cooled onto a thermoelectric module and a thermoelectric module onto heat rejecting elements. There are three widely applied methods that can be Fig 7.1 Adhesive bondng or glueing A thermoelectric module is attached to a header/heat sink or an object to be cool is mounted on to a module by a thermoconductive glue. The thermal contact and mechanical durability strongly depend on glue used. As a rule these are epoxy glue with different fillers which are called to provide a good thermal conductivity. The method of adhesive bonding is referred to methods or rigid fixing. Therefore the thermal expansion agreement of contacting materials (ceramics of the module, heatremoving surface and a material of a cooled object) is necessary. 938

5 8. ADVANTAGES 1. No moving parts The main component of this system is thermoelectric module. It is the component that causes refrigerating effect and heating in the cabin on changing be polarity of supply. 2. Simple and fewer parts required The thermoelectric refrigerator cum beating cabin is made of parts such as thermoelectric module, heat sink, fan, sensor etc. Thus the system is simple and fewer parts are required. 3. No leakage problem No refrigerants are used in this system for refrigeration purpose. Thus no leakage problem will occur. As a result accidents like fire hazards etc. can be reduced. 9. APPLICATIONS 9.1 MEDICAL APPLICATIONS It can be used in medical field as vaccine carrier and also for organ transportation. We can store insulin, polio vaccine, blood, spleen etc. in the system. Nowadays cold boxes are used for organ transportation which mainly makes use of ice. But precise temperature control cannot be maintained and mechanical breakdown of the cells occur in that system. But our system eliminates these drawbacks. 9.2 MILITARY APPLICATIONS This system can be used to transport military equipments which are prone to temperature variations. It can also be used to transport food and beverages at required temperature 9.3 SPORTS FIELD It can be used in sports to store drinks and food for players to prevent the decaying andalso to keep them fresh for use. 10. CONCLUSIONS The portable thermoelectric refrigerator cum beater has been able to successfully achieve the objectives such as portability, implementation of dual mode operation Cheating and cooling) in the same cabin, and noise free operation without any environmental impacts. The COP of the refrigerating system while cooling is obtained as o 305 and that of beating mode is The life of the system will be more as there are no moving components in the system and also maintenance will be less. The system which combines heating and cooling mode in the same cabin finds a wide range of application. The system can be easily charged using different power sources such as AC supply using battery adapter, power from solar panel or it can be charged using adapter provided from cigar lighter ports in cars. Without causing any harm to the environment the system paves a foundation for the innovations in the field of non-conventional refrigeration methods and "green" methods of refrigeration. 11. REFERENCES 1.Surith Nivas M, Vishnu Vardhan D, M Kumar PH, Sai Prasad, Ramya K. 939

6 Photovoltaic Driven Dual Purpose Thermoelectric Refrigerator for Rural India Dual purpose TE refrigerator, International Journal of Advancements in Research &Technology, Volume 2, Issue 6, June Manoj Kumar Rawat, Lal Gopal Das, Himadri Chattopadhyay and subhasis Neogi. An Experimental Investigation. On Thermoelectric Refrigeration system: A Potential GreenRefrigeration Technology, TE refrigerator, Journal of Research And Environmental Development vol. 6 No. 4. April-June Er. R. K Rajput, A Text book of Refrigeration and Air-conditioning, S.K Kataria and sons publication, New Delhi, Dr. R. S Khurumi, J. K Gupta, A Text book of Refrigeration and Air-conditioning. Eurasia Publishing house, New Delhi,

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