Scheme Research Of Wheel Desiccant Air-conditioning Using Waste Heat Of Marine Diesel Engine

Marine transportation is the main transportation vehicle to world trade. Nowadays nearly 90% goods of world trade are transported by ships and it undoubtedly makes great contribution to the development of world economy. Most ships utilize marine diesel engine as the main power plant of propulsion system. Yet the thermal efficiency of marine diesel engine is only about 50%. This is partly due to the fact that a lot of waste heat is taken away by exhaust gas and jacket cooling water etc. Based on waste heat recovery of marine diesel engine and energy-saving technology, this paper analyzes the application of the wheel desiccant air conditioning system on ships.Firstly, the status of the utilization of ship waste heat was summarized. Then the heat balance of marine diesel engine of a certain container ship was calculated, and the proportion of the heat of each part as well as the quality of waste heat was analyzed.Secondly, the basic situation of present marine air conditioning was introduced. The principles of the wheel desiccant air conditioning were explained in graphic details; the application and research status of wheel desiccant in the realm of air conditioning were summarized; and according to the specificity of marine environment, the distribution and utilization status of the ship waste heat, the energy-saving potential of marine wheel desiccant air conditioning system was analyzed. What's more, in stark contrast to traditional marine air conditioning system, the feasibility of wheel desiccant air conditioning system on ships was also discussed.Finally, two solutions of wheel desiccant air conditioning system were proposed: one-stage dehumidification system and two-stage dehumidification. Both solutions take good advantage of the ship waste heat to regenerate the desiccant in the wheel. After comparing the required steam amount needed for desiccant regeneration and the power consumption of the two solutions, two-stage dehumidification scheme which consumes less compressor power was chosen as the system solution. Then the required steam amount of solution two was compared with the steam surplus in ship, and the comparing results showed that the existing boiler in the ship can accommodate the requirement and does not need to be remodeled; and at the same time, the energy-saving potential of solution two was calculated, the calculation results showed that the compressor power consumption of solution two is only 46.6% of the rated compressor power consumption.Two-stage dehumidification scheme proposed in this paper is an effective vehicle to explore a new way for the existing marine air conditioning towards energy-saving; it can use the waste heat of marine diesel engine, saving the energy consumption of marine air conditioning, reducing the ship carbon emissions in operation. And therefore, all of these will definitely reduce carbon emissions and improve the energy efficiency of ships to some extent, thereby meeting the standards of International Maritime Organization (IMO) of marine environment protection.