Research On Marine Air Conditioning Systems Using LNG Cold Energy

To improve the living conditions for crew, the ship air conditioning system is widely installed in ship. However, air conditioning system consumes a lot of ship power and indirectly leads to the environmental pollution. Liquefied natural gas(LNG) power ship has received the favor of the ship market recently, just because it is clean and environmentally friendly. LNG contains a large amount of cold energy, the LNG cold energy is applied to ship air conditioning system that has a strong practical significance.In this paper, the utilization of LNG cold energy for a 3000 DWT multipurpose ship has been studied. The ship fuel is LNG. What's more,we focused on the ship air conditioning system utilizing LNG cold energy. Dynamic load mathematical models of ship air conditioning system were established to calculate load by TRNSYS based on heat balance theory, at the same time, crew, lighting, equipment should be considered. Through simulation results, we found that the total annual maximum load is 10.76 kW for ship cabins,the cooling time is 4480 h, accounting for 55.7% of the total time of the year. In all cabins,The maximum load is 1.998 kW for the cab Room7. Cooling load reaches maximum at 4p.m and reaches minimum at 7 a.m every day for each cabin. The results provide basic design datas for the LNG cold energy air conditioning system.To recover and utilize LNG cold energy for a 3000 DWT multipurpose ship, three conceptual air conditioning designs are proposed. Ship air conditioning system utilizing LNG cold energy with one circulation; ship air conditioning system utilizing LNG cold energy with two circulations; ship air conditioning system utilizing LNG cold energy.Based on “black box” theory, global simulation model for the ship air conditioning system utilizing LNG cold energy is established by adopting the method of modularization in Aspen Plus.The practical application feasibility and exergy efficiency are goal orientations for simulation. The three designs were carried out by thermodynamic analysis. The parameters,pressure, temperature, enthalpy, entropy and exergy were calculated respectively. The simulation results showed that the improvement scheme S2 for ship air conditioning system utilizing LNG cold energy with two circulations has stronger practical operability. And the heat exchanger exergy efficiency of HE1 is 25.05% for the improvement scheme S2. For the ship air conditioning system S2 utilizing LNG cold energy with two circulations, R404 a is as primary coolant, 60% ethylene glycol is as the secondary coolant. Annual cost method is a comprehensive equipment economic analysis method which concerning equipment initialinvestment and operational costs. Based on the method, the conventional vapor compression refrigeration and air conditioning utilizing LNG cold energy for 3000 DWT multipurpose ship were analyzed and evaluated. The calculation results showed that the annual cost of the conventional vapor compression refrigeration ship air conditioning is 56350 yuan, the annual cost of ship air conditioning utilizing LNG cold energy is 31190 yuan. The annual cost decreased 25160 yuan. So the LNG cold energy ship air conditioning system has a good economy.An experiment scheme has been designed for the ship air conditioning system S2 utilizing LNG cold energy with two circulations. The designs and the selections of the key components have been carried out for the LNG vaporization system, the refrigerating medium circulatory system, the cylinder cooling water heat recovery system, the air conditioning ventilation system. The experiment test system has been built in a ship, at the same time, the measurement devices have been selected. The experiment framework has been made.