Cogeneration and Diesel Electric Power Production

Abstract

We have developed a data acquisition system to both monitor the efficiency of a diesel-electric generator set in producing electricity and to evaluate its performance as part of a cogeneration system for producting both heat and electricity. We have used this system to evaluate the performances of a 45 kW system consisting of a Mitsubishi engine coupled to a Stamford generator and an 80 kW Caterpillar system.

We find that, even though the efficiency of a generator set in producing electricity decreases appreciably as the electric load decreases, the cogeneration efficiency is relatively insensitive to load. The latter includes both the electric power produced and the rate of heat recovery from the jacket water as benefits. We also found that the engine temperature as measured by jacket water temperature can be maintained at high levels even at low loads if the cooling mechanism is restricted. We accomplished this in a laboratory situation by decreasing the water flow through an externally-mounted heat exchanger used to provide a source of cooling for the engine. We also found that the 80 kW cogeneration system at Coldfoot provided about one-third of the space heat needed by the maintenance shop. The payback period was less than 2 years for this system with about 2200 gallons of fuel oil being saved annually because of heat recovery from the jacket water.

Volume I contains the main body of the report; appendices are contained in Volume II.