Influencing factors of air states in liquid desiccant dehumidification systems

doi:10.11949/0438-1157.20201495

Abstract

Abstract:

The influence mechanisms of circulation solution flow (G_cir), cold/heat capacity (Q_c/Q_h) and systemic process on the air state changes and dehumidification effect in typical cross-flow liquid desiccant dehumidification systems were researched. Through simulation and analysis, the air process lines in the enthalpy and humidity diagram under different working conditions were exhibited, and the influence degrees of various factors were compared. The results show that under design conditions, the liquid desiccant system achieves optimal dehumidification effect when G_cir is about 0.05 kg/s; as the total Q_c and Q_h increase from 29.4 kW to 48.9 kW with close ratio, the dehumidification amount increases from 3.7 g/kg to 5.7 g/kg; in the different processes, the liquid desiccant dehumidification amount is relatively large when the cooling object is solution. Compared with G_cir and Q_c/Q_h, the systemic process has greater influence on air state changes and dehumidification effect. The air process lines in each process have significant characteristics, and the liquid desiccant process is the core factor that influences the air state changes and the dehumidification effect.

Key words: solution, mass transfer, model, dehumidification effect, regeneration

摘要：

研究典型叉流式溶液除湿系统中，溶液循环流量（G_cir）、冷/热量（Q_c/Q_h）和系统流程对除湿/再生空气状态变化和除湿效果的影响机制。分析不同工况下空气在焓湿图中的过程曲线特征，比较各因素影响程度。结果表明，在设计条件下，当G_cir约为0.05 kg/s时，溶液除湿系统达到最佳除湿效果；当Q_c、Q_h比例接近，总量由29.4 kW增加至48.9 kW时，系统中除湿量由3.7 g/kg上升至5.7 g/kg；不同流程中，当冷却对象为溶液时，溶液除湿效果较好。相较于溶液除湿系统中G_cir和Q_c/Q_h，溶液除湿流程对空气状态变化和除湿效果的影响程度较大。空气过程曲线在各流程下具有显著特征，溶液除湿流程是影响空气状态变化和除湿效果的核心因素。

关键词: 溶液, 传质, 模型, 除湿效果, 再生

CLC Number:

TU 834.9

QU Hongshuo, ZHANG Lun, ZHANG Xiaosong, JI Wenbin. Influencing factors of air states in liquid desiccant dehumidification systems[J]. CIESC Journal, 2021, 72(S1): 210-217.

曲泓硕, 张伦, 张小松, 纪文彬. 溶液除湿系统空气状态影响因素[J]. 化工学报, 2021, 72(S1): 210-217.

Figures/Tables 9

Fig.1 Heat and mass transfer model between air and liquid desiccant with cross-flow path

Fig.2 Comparison of simulation results and data obtained in extant experiments

Fig.3 Systemic diagram of one typical liquid desiccant dehumidification device

Table 1 Initial parameters of liquid desiccant system.

项目	参数	数值
回风	温度	26℃
	含湿量	12.7 g/kg
	流量	1 kg/s
新风	温度	35℃
	含湿量	21.4 g/kg
	流量	1 kg/s
溶液	G_deh	1 kg/s
	G_reg	1 kg/s
除湿器/再生器	NTU_m	2
冷源	Q_c	10 kW
热源	Q_h	10 kW
溶液换热器	换热效率	55%

Fig.4 Variation of air process states with Gcir in liquid desiccant system

Table 2 Variation of dehumidification solution S2 and regeneration solution S6 status with Gcir

C_cir/(kg/s)	S₂		S₆
C_cir/(kg/s)	温度/℃	浓度/%	温度/℃	浓度/%
0.02	19.4	38.2	42.1	42.7
0.05	20.4	39.8	41.1	41.7
0.1	21	40.3	40.4	41.2
0.2	21.7	40.4	39.7	40.9
0.5	22.8	40.3	38.4	40.5
1	23.8	40.2	37.3	40.2
2	24.7	40.0	36.4	40.0

Fig.5 Variation of air and solution states under different combinations of Qc/Qh

Fig.6 Liquid desiccant dehumidification effect with different combinations of Qc/Qh

Fig.7 Variation of air process lines with cooling/heating modes

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