Research On Liquid Desiccant Air Handling Device Driven By Heat Pump

Liquid desiccant air handing device driven by heat pump, which can be used without restiction of climatic conditions and geographical regions, is the most likely to promote in large-scale application. The lack of research on structure design, performance optimization, adjustment method of supply air prameters and the best operation strategy during the previous research, results in a greatly restricting of the expansion and application on liquid desiccant technology. This paper carried out the following studies:Firstly, based on the simulation platform program which was verificated by the experimental data, the air handling process parmaters and performance of different liquid desiccant device is analyzed The optimization principle of liquid desiccant air handing device driven by heat pump is proposed. The best structure of the liquid desiccant device must be the structure which can make the heat exchange of each unit matches its heat and mass transfer area. And, the solution flowrate of local cycle must match the flowrate of processed air. Meanwhile, the heat transfer area of the heat recovery plant exchanger should be maximizd as far as possible. The solution flowrate of main cycle must be minimized under the conditions of ensuring the normal condition of the main cycle.Secondly, the enthalpy difference driving forceΔh and the relative humidity difference driving forceΔ? between the desiccant solution and air have been analyzed. It is found that the supply air parameter changed along the constant enthalpy line when the enthalpy difference driving force was constant, and the supply air parameter changed along the constant relative humidity line when the relative humidity difference driving force was not changed. Then, the control strategy of supply air is concluded: the enthalpy of solution is adjusted by controlling the cooling capacity of the heat pump, thus the supply air enthalpy can be adjusted to the set value, and then by controlling the amount of water added to the regeneration unit to adjust the solution concentration, the relative humidity of supply air can be adjusted to the set value.Thirdly, the zone-divding method of outdoor air intet parameters in the psychrometric chart is proposed. Accroding to the energy consumption comparation of the outdoor air in different zones under different operation method, the best operation strategy of liquid desiccant air handling device driven by heat pump during whole year is concluded. The relationship between the performance of the air handling deviece and the enthalpy of the outdoor air is pointed out. And, the efficiency of the air handling device is much higher in hot and humid climate conditions.Finally, based on the above studies, the application method, device performance and energy saving data in practical application is introduced. The liquid desiccant outdoor air handling device driven by heat pump has been used in more than 50 applications in the domestic public construction projects, with a total area of over 1.62 millon m~2, and the measured operating cost data shows that more than 30% energy consumption can be saved compared to the conventional air-conditioning system. The liquid desiccant air handling units driven by heat pump has been used in more than 20 projects in process of constant temperature and humidity air conditioning system, application area of nearly 100,000 m~2, the measured energy savings up to 40%~70%.