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Short Paper Proc. of Int. Colloquiums on Computer Electronics Electrical Mechanical and Civil 2011

Power Analysis by Calorimetric method in a Microwave Oven with Various Loads. Smitha I.S1, Chris Cyril1, Devi Prasad.V.R1and K.Rajeev kumar2 1

Federal Institute of Science and Technology, Cochin, India Email: smithasivak@fisat.ac.in, chris@fisat.ac.in , deviprasadvr@gmail.com 2 Cochin university of science and technology, Cochin, India Email: rajeev@cusat.ac.in The loads used in the calorimetric method include coconut oil and engine oil. Both are having unique chemical structures.

Abstract — — - As a part of study of converting a domestic Microwave oven to a low cost but effective Microwave plasma generation system, we have carried out calorimetric calibration of an oven for various heating loads. The effect of the parameters like supply voltages to magnetron, load volume and the heating time on the absorbed power was found out. The calorimetric calibrations were carried out with various heating loads like coconut oil and engine oil. It was observed that coconut oil absorbed maximum microwave energy whereas engine oil absorbed minimum. The study points out the differences between coconut oil and engine oil with respect to their heating characteristics under exposure to microwave energy.

II. MATERIALS AND METHODS 

Microwave oven: - Whirlpool Magic cook 20S, 2.45GHz -230V/50Hz, and rated input 1100W. Output power consumption 700W- 20L cavity volumeCavity dimensions, 196x292x295 mm.  Dimmer stat, thermometers, borosil glass beakers and stop watch.  Engine oil ( HP racer 2T) , virgin coconut oil Fig.1 shows the experimental setup for the plasma deposition unit.

Index Terms— Microwave plasma, Magnetron input voltage, absorbed power, Microwave oven.

I. INTRODUCTION It is well known that Microwave plasma has several advantages over DC and RF plasmas for processing and surface modification of materials. A domestic microwave oven, can be modified to develop a low cost microwave induced plasma deposition system which can be used to deposit thin films of various materials and to produce nano structures of materials like ZnO. Magnetron is the basic source for microwaves at 2.45GHz. A quartz tube placed inside the chamber acts as the applicator which when exposed to microwaves generates a plasma inside. Plasma is formed by the interaction of microwaves with the gases at appropriate low pressure inside the quartz tube. Vacuum system consists of a Rotary vacuum pump, vacuum lines, valves and Pirani gauge. As part of this we have done calibration of the microwave chamber with various types of heating loads. The study was conducted by following the International Standards set by IEC 705(1988). This standard gives a relation between microwave power applied and increase of temperature in loads, as

1. Air inlet. 2. Plasma Chamber 3. Quartz tube 4. Pirani Gauge 5. Vacuum pump 6 .Substrate holder Fig.1 Plasma deposition unit.

The setup can be used to generate plasma in the quartz tube. In the presence of plasma, chemical deposition on a glass slide is made possible. Plasma is a substance similar to gas in which a certain portion of the particles are ionized. It does not have a definite shape or volume unless enclosed in a container. Most artificial plasma generated in laboratories and industries are generated by the application of electric and/or magnetic field.

P= where, P: Microwave power used for heating in watts. V: Volume of load within the cavity in mL C: Specific heat capacity in KJ/Kg.K

: Density of the fluid in kg/m

A. Procedures for calorimetric power analysis on heating loads.



t: Time of heating(s) Mean temperature rise (K)

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Take V ml of the heating load (engine oil or coconut oil) in a borosil glass beaker. Record the initial temperature (T1) using thermometer. Place the

Short Paper Proc. of Int. Colloquiums on Computer Electronics Electrical Mechanical and Civil 2011 Fig.2 shows the average power analysis graph for coconut oil as heating load with variable quantity and time.

container inside the oven. Switch on the oven, and heat the load for time of‘t’ seconds. After ‘t’ seconds oven is switched off and the beaker is taken out carefully. Stir the contents for 20 seconds. And find the final temperature (T2). The output power is determined by the equation

where, Mf and Mg are the mass of the fluid and the beaker respectively. Cp-f and Cp-g are the specific heats of the fluid and beaker respectively. is the rise in temperature and t is the time in seconds. III. EXPERIMENTS AND RESULTS

Fig.2 Average power analysis for coconut oil.

The average power absorbed for various values of load parameters were calculated. Magnetron input voltage was kept at the rated voltage of 230V 50Hz by the dimmer stat. Power absorbed was calculated using the IEC 705 formula.

Vegetable oil based lubricants offer significant environmental benefits with respect to resource renewability, low toxicity, and provide satisfactory performance in a wide array of applications. Vegetable oils in general have excellent properties such as high viscosity index, high lubricity, high flash point, and low evaporative loss with regard to their use as base oils for lubricants. On the negative side, they are known to possess low thermal, oxidative and hydrolytic stabilities and poor low temperature characteristics. The poor cold flow properties of vegetable oils can be attributed to their unique molecular structure, namely, triacylglycerol structure.. Such macro crystals restrict the easy flow of the system due to loss of kinetic energy of individual molecules during self stacking. During heating, the chain distance increases so the power absorbed increases.

A. HEATING LOAD 1: Power absorbed with heating load as Coconut oil. For all calculations cf = 1.67KJ/KgK, cg = 0.74J/KgK.

TABLE .II POWER ANALYSIS

100ML COCONUT OIL AS 120 SECONDS.

B. HEATING LOAD 2: Power absorbed with heating load as Engine oil. For all calculations cf = 2.09K J/KgK, cg = 0.74 KJ/KgK HEATING LOAD WITH

HEATING TIME OF

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Short Paper Proc. of Int. Colloquiums on Computer Electronics Electrical Mechanical and Civil 2011

Fig.3 shows the average power analysis graph for Engine oil as heating load with variable quantity and time. Fig.4 Average power for coconut and Engine oil.

CONCLUSIONS Different heating loads were put to test for power analysis. It was found that absorbed power varies with type of heating load. Among the two oils, Coconut oil exhibited 50% increase and engine oil 300% increase in absorbed power as time of exposure to microwave was increased from 60 to 180 seconds. From figure 2 it is evident that the power absorbed by the coconut oil tends to approach a steady value. Engine oil does not exhibit this saturation tendency within the time frame of the experiment . It appears from figure 3 that it can maintain linear relationship for a wide range of temperature. On the other hand the overall power absorption by engine oil is very much less compared to an equal mass of coconut oil.

Fig.3 Average power analysis for Engine oil.

One of the most important properties of motor oil in maintaining a lubricating film between moving parts is its viscosity. The viscosity must be high enough to maintain a lubricating film, but low enough that the oil can flow around the engine parts under all conditions. The viscosity index is a measure of how much the oil’s viscosity changes as temperature changes. A higher viscosity index indicates the viscosity changes less with temperature than a lower viscosity index.. The rise in power absorption of the engine oil as heating load is lower when compared to other heating loads on account of the additives which are added (Viscosity Modifiers).

REFERENCES [1] Jirina Housova and Karel Hoke, “Microwave Heating – the Influence of Oven and Load Parameters on the Power Absorbed in the Heated Load”, Food Research Institute, Journal of food science, volume 20, No3: Page 117-124. [2] Klamman and Dieter, “Lubricants and Related Products”, Verlag Chemie, 1984, ISBN 0-89573-177-0. [3] Leo Mendel D Rosario and Roy B. Tumlos “Calorimetric Measurements of the Output Power of the 2.48 GHz Commercial Magnetron”,,Plasma Physics Laboratory,science Dilman July-December 2004 [4] Muhammad shanawas and Saghir Ahmed sheikh , “ Analysis of viscosity of jamun fruit juice, squash and jam at different compositions to ensure the suitability of processing applications” ,International journal of plant physiology and bio chemistry, Volume 3(5), pp 89-94 May 2011. [5] Gerhard Knoth , “Historical perspectives on vegitable oil based diesel fuels”,Volume 12, November 2001, pp1103. [6] David smith V.K., “Panasonic microwave inverter HV power supply , users manual. [7] L.A. Campanone, N.E. Zaritzky “Mathematical analysis of microwave heating process”,Journel of food Engineering 69(2005) Pages 359-368

C. Comparison of various heating loads.

Fig.4 shows the power analysis graph for time Vs average absorbed Power for various heating loads such as coconut oil, and engine oil.

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