thermal performance of kenya defence forces mobile diesel cooker

Abstract

Kenya Defence Forces (KDF) developed a diesel and LPG mobile field cooker (DEFKITCH) in the year 2010 capable of cooking food for over two hundred soldiers within a cooking session of one hour. The equipment was intended to reduce high usage of firewood for cooking in order to save Kenyan forests. Its commercialization and mass production was launched in the year 2012 at Kenya Ordnance Factories Corporation (KOFC) in Eldoret. Since the cooker was invented, no experimental assessment had been done to ascertain its thermal performance and emission levels. The objective of this research was to experimentally evaluate the combustion and thermal efficiencies of the DEFKITCH cooker by comparing its thermal performance in Water Boiling Test (WBT) with other similar cookers like ARPA kerosene cooker;- analysing emission levels of the cooker and suggesting possible modifications aimed at improving DEFKITCH overall performance. Thermal efficiency was investigated for diesel fuel by conducting WBT. Parameters used were: heating time, temperatures and fuel consumption. Average thermal efficiencies computed from the results ranged from 60.37 percent to 65.86 percent using the 24 gallons cooking pots while a lower value of 42.69 percent was obtained using the 12 gallon pot on the same cooker. These values were found to be higher compared to the ARPA cooker which was an earlier model kerosene burner whose thermal efficiency was found to be 40.0 percent. However, this research established that LPG could not burn with sufficient flame to support WBT and therefore thermal efficiency could not be obtained. Average diesel consumption rate was found to be 0.8 litres per burner in one hour. Combustion efficiency of the cooker was determined using TESTO flue gas analyser and the overall value was determined as 69.0 percent while burning diesel and 46.5 percent while burning LPG. Emission levels for CO and CO 2 were determined as 172.7 ppm and 49,500 ppm (4.95 percent) respectively while using two burners on diesel. The CO level was found to be within the recommended maximum emission limit of 400 ppm air free basis according to National Comfort Institute Incorporation, 2008. The cooker was found to be economical in diesel consumption per unit amount of work and recommended for use without adaptor.