However , because of the relatively short period of its domestic development , and limitations of its techniques , the operation cost of the units is quite high . as a result , the energy conservation and optimal control of direct - fired absorption chillers using waterlithium bromide as refrigerant becomes a hot topic in the research area of havc communities 近年来直燃式溴化锂吸收制冷机应用日益广泛,但是由于此类机组在国内的发展历史较短,以及自身技术特点限制,造成机组运行费用高的现象,因此它的节能优化控制是目前hvac领域热门的研究话题。