ENGINE PRE-WARMING HEAT STORAGE SYSTEMS AS SOLUTIONS TO COLD-STARTING PROBLEMS OF DIESEL ENGINES

Abstract

The system described in this article provides a solution to the cold-starting problems of Diesel engines by recycling the waste heat of the vehicle produced during operation. The heat regained from exhaust gases and/or from the coolant is stored in a heat storage system connected to the cooling system. The pre-warming taking place a few minutes prior to starting in also realised through the cooling system by applying a battery-fed water pump. The mass and the volume of the heat storage installation is limited, thus in order to attain the adequate heat capacity a storage material of high energy density is needed. It has been shown during the theoretical examination of systems with phase-changing storage materials that the traditional heat storage construction does not let the phase changing end in a few minutes, thus only a part of the stored latent heat can be regained. Rapid pre-warming can be attained by using an experimental installation of the sen-sible heat storage system containing a mixture of water and glycol, mounted in an Ikarus bus and by applying intensive circulation, which results in an efficient way of utilising the stored heat. It is mainly at the pistons that the rapid pre-warming of the engine leads to an increase of temperature. As consequence, the friction at the pistons decreases and the starting of the engine requires less starting power. The higher temperature of the cylinder walls is also more favourable for burning and the end temperature of compression needed for self ignition is more easily attained. During the experiments in the cold wind tunnel, the Diesel engine started firmly every time after the pre-warming procedure of the heat storage system had taken place.