Asian Journal of Microbiology, Biotechnology & Environmental Sciences Paper

THERMAL PROPERTIES OF DIFFERENT FORMS OF PIGEON PEA AT SELECTED MOISTURE CONTENTS

P. HEMASANKARI, R.VISWAKARMA, D. MRIDULA DEVI AND R.KAILAPPAN

Abstract

The three forms of pigeon pea viz. unhusked, husked and split form dhal taken for determination of thermal properties viz. thermal conductivity, thermal diffusivity, thermal effusivity, thermal resistivity and specific heat at different moisture contents ranging from 10% to 20% mc. (10%, 16%, 18% and 20%). The pigeon pea grains in all its three forms were subjected to moisture content determination using hot air oven method. The pigeon pea grains were added with water to make up the moisture content by distilled water addition using formula method. Then moisture content were determined using hot air oven method. Thermal properties were determined using lab model thermal conductivity meter. Thermal conductivity range of value in dehusked pigeon pea is 0.056 to 0.06W/m °k, in unhusked pigeon pea is 0.049-0.059W/m°k ranging in moisture content from 10% to 20%. The thermal conductivity values increases from 0.056 to 0.06W/m°k in dehusked and in unhusked it increases from 0.049 to 0.059W/m°k from 10% to 20% mc. In unhusked the thermal conductivity values are lower as compared to dehusked pigeon pea and it varies with moisture content also. At low moisture content of 10% and in unhusked the lowest is found this may be due to the presence of outer layer and with less moisture the level of conductivity is low. This is not the same result as in thermal resistivity and in dehusked range is 1681-18.02KJ/kg °C, in unhusked the range of values is 16.88-20.3 KJ/kg oC Specific heat is less in unhusked pigeon pea, 2.46KJ/kg °C. Thermal effusivity range is 11.80-12.22Ws/m2°k in de -husked and in unhusked,11.00-12.07Ws/m2°k. Thermal effusivity increases with increase in moisture content from 10% mc to 20% mc. Thermal conductivity decrease in unhusked pigeon pea is 5% as compared to dehusked pigeon pea. Thermal resistance in dehusked is 7.32% less as compared to unhusked pigeon pea. Thermal effusivity of dehusked, 4.58% is more as compared to unhusked pigeon pea. Specific heat in dehusked pigeon pea, 2.0% as compared to unhusked pigeon pea. Thermal diffusivity of unhusked pigeon pea is less by 9.76% as compared to dehusked pigeon pea. The values were significant at 5% level of significance and analysis were done using SPSS-16.0 software and design expert software, 12.0 version.