6.3 Ef fi cient Liquid Desiccant Air-Conditioning Systems
6.3.2 Liquid Desiccant Systems Combined with Heat Pumps
Figure6.29shows a liquid desiccant system combined with a heat pump [5]. In this system, the evaporator is used to cool the strong liquid desiccant during dehu- midification and two condensers are used to heat the weak liquid desiccant and scavenging air, respectively, during regeneration. To reduce the cooling load for evaporator as well as heating load for condenser, an interstage cycle is added between the dehumidifier and the regenerator.
Under summer conditions, diluted solution from the weak solution tank is divided into two parts. One part of the diluted solution goes through the first condenser after mixing with a part of the concentrated solution from the strong solution tank. Then, the mixed solution heated by the first condenser enters the regenerator and contacts with the scavenging air heated by the second condenser.
Fig. 6.28 Liquid desiccant system combined with evaporative cooling producing cold water and dry air
Fig. 6.29 Liquid desiccant system combined with heat pumps having two condensers
After regenerator, the mixed solution is concentrated and flows into the strong solution tank. The other part of the diluted solution from the weak solution tank is mixed with a part of concentrated solution and cooled by the evaporator afterward.
The cooled liquid desiccant enters the dehumidifier to produce the cold and dry air, which is supplied to the air-conditioning room to control the indoor temperature and humidity.
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Numerical and Experimental Investigation on Solid Desiccant-Assisted Mobile
Air-Conditioning System
Hoseong Lee and Yunho Hwang
Abstract In the conventional mobile air-conditioning system, evaporating tem- perature should be lower than the dew point temperature of cabin to control the temperature and humidity. Thus, reheating of the air is necessary. These two factors could increase the fuel consumption of the system. To overcome these issues, a solid desiccant-assisted mobile air-conditioning system is proposed and investi- gated. It is proposed to apply the solid desiccant to the mobile air-conditioning system to handle most of latent load, while the vapor compression cycle (VCC) handles the remaining latent load and sensible load. The model of the proposed concept is developed and validated with experimental data. Then, the possible configurations of the solid desiccant-assisted mobile air-conditioning system are discussed. Lastly, the proposed system is experimentally investigated with various operating conditions.
Keywords Solid desiccant Desiccant wheelSSLC MAC
Nomenclature Symbols Eff Efficiency h Enthalpy P Pressure
H. Lee
Department of Mechanical Engineering, Korea University, Seoul, Republic of Korea
Y. Hwang (&)
Center for Environmental Energy Engineering, University of Maryland, 3157 Glenn L. Martin Hall Bldg., College Park, MD 20742, USA e-mail: yhhwang@umd.edu
©Springer Nature Singapore Pte Ltd. 2017
N. Enteria et al. (eds.),Desiccant Heating, Ventilating,
and Air-Conditioning Systems, DOI 10.1007/978-981-10-3047-5_7
167
Q Heat transfer capacity T Temperature
W Work input X Quality q Density
Acronyms
AC Alternating current COP Coefficient of performance DC Direct current
DP Pressure drop DW Desiccant wheel
EES Engineering Equation Solver FPI Fins per inch
MAC Mobile air-conditioning MFR Massflow rate
MRC Moisture removal capacity PR Pressure ratio
RH Relative humidity RPM Revolutions per minute SD Solid desiccant
SSLC Separate sensible and latent cooling TXV Thermal expansion valve
VCC Vapor compression cycle VFR Volumetricflow rate
Subscript amb Ambient comp Compressor cond Condenser DW Desiccant wheel evap Evaporator exp Experiment in Inlet isen Isentropic out Outlet
reg Regeneration-side sim Simulation vol Volumetric