Experimental study on application of U-shaped three-dimensionalheat pipes in energy-saving renovation of air conditioningunits in cigarette factories

The production workshop of the cigarette factory has strict requirements for temperature and humidity control. The traditional constant temperature and humidity air conditioning system has high energy consumption due to the cold and heat offset phenomenon. In view of this problem, this paper proposes to add a U-shaped three-dimensional heat pipe to the modular air handling unit. Through the synergistic effect of its pre-cooling section and reheating section, the U-shaped three-dimensional heat pipe recovers waste heat in the air treatment process, the cooling load of the surface cooler is reduced, and the steam reheating is reduced to reduce energy waste. The experiment takes an air conditioning unit with a supply air volume of 6 000 m3/h and an outdoor air ratio of 10% as the research object, and conducts mathematical model analysis and enthalpy difference laboratory tests. The results show that the U-shaped three-dimensional heat pipe reduces the cooling capacity of the surface cooler by 23.8% through pre-cooling air, and can save 4 tons of standard coal in 120 days of operation in summer. The additional energy consumption caused by the increase in fan resistance only accounts for 2.3% of the total energy saving, and the economic and environmental benefits are significant.