Experimental Investigation of the Thermal Performance of Kenya Defence Forces Mobile Diesel Cooker

Kenya Defence Forces (KDF) invented a diesel mobile field cooker (DEFKITCH) in the year  2010 capable of serving over two hundred soldiers in military camps and in operation areas (patent number KE 0642 dated 28 April 2014). The cooker was designed with three different sizes of cooking pots made of grade 304 stainless steel: (i)-24 gallon light duty with uniform wall thickness of 3 millimetres (ii)-24 gallon heavy duty with wall thickness of 3 millimetres and bottom thickness of 6 millimetres (iii) -  12 gallon pot with wall thickness of 3 millimetres. The cooker was commercialized in 2012 but since then no experimental assessment had been done to ascertain its performance and emission levels. Therefore this research sought to investigate the thermal performance of the cooker by experimental assessment of the combustion and thermal efficiencies as well as the level of emission of CO and CO2. Thermal efficiency was investigated by conducting Water Boiling Tests (WBT) where parameters like heating time, temperatures and fuel consumption rate were recorded. Average thermal efficiencies computed from  the results ranged from 60.37 percent to 65.86 percent using the 24 gallon cooking pots while a lower value of 42.69 percent was obtained using the 12 gallon pot on the same cooker. The average thermal efficiency was found to closely compare with those of  other cookers in the open literature  –ranging from 58  –  68 percent. Average diesel consumption per burner was found to be 0.8 litres in one hour which was found to be sufficient to prepare a meal for approximately two hundred people. Combustion efficiency  of the cooker was determined using TESTO flue gas analyzer and the overall value was determined as 69.0 percent. Emission levels for CO and CO2  were determined as 172.7 ppm and 4.95 percent. These were found to be within the recommended maximum emission level of 400 ppm according to National Comfort and Institute, Incorporation 2008. The cooker was found to be economical in diesel consumption per unit amount of work and a better substitute to using firewood for cooking food for a large group of people especially in remote locations such as military operation areas. Keywords  -  Combustion efficiency, Emissions, Kenya Defence Forces, Mobile Field Diesel Cooker, Thermal efficiency