EXPERIMENTAL AND CFD ANALYSIS OF A SOLAR BASED COOKING UNIT

Transcription

1 EXPERIMENTAL AND CFD ANALYSIS OF A SOLAR BASED COOKING UNIT I N T R O D U C T I O N Among the different energy end uses, energy for cooking is one of the basic and dominant end uses in developing countries. An enormous amount of energy is thus expended regularly on cooking. Energy requirement for cooking accounts for 36% of total primary energy consumption in India. The usage of LPG stored in cylinders as a fuel source has become more prevalent in the developing and developed countries of the world in recent years. Non-renewable energy sources are being rapidly depleted. There is an urgent need to develop an appropriate technology for cooking based on new and renewable energy sources. solar cookers are best substitute for conventional cooking devices. Institute for Energy Studies 1 Anna University

2 EXISTING INDIRECT TYPE SOLAR COOKERS IN INDIA (a) Sathyabama University, (b) Tirumala Devasthanam (c) Auroville (d) Rajasthan (e) Shirdi (f) Sringeri and (g) Ladakh Institute for Energy Studies 2 Anna University

3 OBJECTIVE OF THE WORK to develop a solar system integrated with a cooking unit through a PCM based thermal storage tank and to analyze the discharging performance of the system. to analyze the performance of the newly developed cooking unit by using the CFD analysis. Institute for Energy Studies 3 Anna University

4 PURPOSE OF THE CFD ANALYSIS Solar PTC Cooking Units TES Tank PCM Balls Experimental Setup (1) Parabolic trough collector (2) TES tank (3) Cooking unit (4) Pump (5) Data acquisition unit (6) Computer (7) Valve Institute for Energy Studies 4 Anna University

5 C F D ANALYSIS Isometric view Computational Grid Institute for Energy Studies 5 Anna University

6 CFD ANALYSIS - BOUNDARY CONDITIONS The velocity boundary condition is used at the inlet, and the pressure boundary condition is used at the outlet. Other sides of the fluid domain are applied with the wall boundary condition. The bottom and side surfaces of the cooking unit are insulated and the top plate surface transfers the heat by convection, with a known outer surface heat transfer coefficient `h at the circular center portion. The remaining portion of the cooking surface is considered with low heat transfer coefficient. In the simulation analysis, an inlet HTF velocity and temperature of m/s and the actual inlet temperature measured from the experiment at a given time are used for the analysis. The CFD analysis is also performed for various outer surface heat transfer coefficients 'h, for the circular center cooking portion (20, 100, 200 W/m 2 K). Institute for Energy Studies 6 Anna University

7 RESULTS AND DISCUSSION Variation of the HTF at the inlet and outlet of the cooking unit and instantaneous heat transfer rate with respect to time Energy flow diagram for the cooking unit integrated with the TES tank Institute for Energy Studies 7 Anna University

8 RESULTS AND DISCUSSION (a) (b) Heat transfer rate for (a) cooking surface (b) (c) non-cooking surface and total top plate surface (c) Institute for Energy Studies 8 Anna University

9 RESULTS AND DISCUSSION Average heat transfer rate Heat transfer rate comparison for different heat transfer coefficients Institute for Energy Studies 9 Anna University

10 C O N C L U S I O N The following conclusions are made from the present research. The flat type configuration selected for the present investigation is suitable for the preparation of some of the Indian dishes like dosa and chappathi. The heat transfer capacity of this cooking unit is in the range of 100 W to 500 W based on the variation in the `h. The CFD analysis performed is also validated with experimental results. In order to prepare all kind of food items using solar energy, the concept of annular gap cooking unit can be extended to other cooking unit configuration. Institute for Energy Studies 10 Anna University