Desiccant Solution Temperature Research Articles

Parametric study of a single cycle two-stage structured packing counter flow air dehumidifier using two feeding desiccant solution lines

The performance analysis of a two-stage air dehumidifier using two feeding lines of liquid desiccant solution is introduced in the present work. The process air is deeply dehumidified through two absorption counter flow stages through dehumidifier stages a and b using a single desiccant cycle. The theoretical model is validated and show good agreement to study the effect of different operating parameters on the performance of the proposed system. For different operating parameters (air and solution mass flow rates, inlet air humidity ratio and temperature, desiccant solution inlet concentration and temperature), the presented results reveal a great enhancement in dehumidification performance by using the proposed system. At the same desiccant solution mass flow and when the inlet air humidity ratio is changed from 0.016 to 0.024kgvkgda-1, an average increase of 49.2% in εy and 48.9 in MRR is achieved compared to a single stage air dehumidifier.

Experimental Investigation of Electrical Conductivity of Liquid Desiccant Solution

Liquid desiccant cooling system is a novel air conditioner with good energy saving potential, which should be a promising choice to meet the needs of cooling and moisture loads. Among all regeneration methods, ED regeneration method should be a promising choice for liquid desiccant cooling system. In this paper, systematic experiments were carried out to investigate the electrical conductivity of desiccant solution. Experimental data of electrical conductivity of desiccant solution is acquired in the experiment, which will be greatly helpful to the energy analysis of ED regeneration system. The experimental results show that the energy consumption in the concentrated chambers is more than others for ED regeneration system cells. Moreover, increasing the temperature of desiccant solution may be a measurement to reduce the energy consumption of ED regeneration system.

An experimental study of structured packing dehumidifier/regenerator operating with liquid desiccant

The present work presents an experimental investigation on the performance of the structured packing cross flow desiccant dehumidification system (DDS). This system is referred as DDS; its heart is the dehumidifier/regenerator. It is used to meet a latent heat load by air dehumidification. Calcium chloride (CaCl 2) solution is used as the working desiccant material in this system. The structured packing has a density (specific surface area) of 390 m 2/m 3, corrugation angle of 60° and void fraction of 0.88. The effect of relevant parameters such as air flow rate, desiccant solution flow rate, desiccant solution temperature and concentration and packing thickness on the performance of the system is studied. The performance of the system is evaluated using the mass transfer coefficient, moisture removal rate (MMR), effectiveness and the coefficient of performance (COP). The remarkable increase of mass transfer coefficient and MRR for both deh/reg is observed by increasing both air and solution flow rates. Eventually, the payback period (PP) of the DDS is 11 months with annual running cost savings (Δ C RC) of about 31.24% compared with vapor compression system (VCS) dehumidification. The overall environmental impacts of DDS are nearly 0.63 of VCS. This may emphasize the need of incorporating a desiccant system along with air conditioning applications.

Experimental study on dehumidifier and regenerator of liquid desiccant cooling air conditioning system

A new type of air conditioning system, the liquid desiccant evaporation cooling air conditioning system (LDCS) is introduced in this paper. Desiccant evaporation cooling technology is environmental friendly and can be used to condition the indoor environment of buildings. Unlike conventional air conditioning systems, the system can be driven by low-grade heat sources such as solar energy and industrial waste heat with temperatures between 60 and 80°C. In this paper, a LDCS, as well as a packed tower for the regenerator and dehumidifier is described. The effects of heating source temperature, air temperature and humidity, desiccant solution temperature and desiccant solution concentration on the rates of dehumidification and regeneration are discussed. Based on the experimental results, mass transfer coefficients of the regeneration process were experimentally obtained. The results showed that the mean mass transfer coefficient of the packing regenerator was 4g/(m2s). In the experiments of dehumidification, it was found that there was maximal tower efficiency with the suitable inlet humidity of the indoor air. The effective curves of heating temperature on the outlet parameters of the regenerator were obtained. The relationships of regeneration mass transfer coefficient as a function of heating temperature and desiccant concentration are introduced.

04/03136 Numerical studies and experimental observations of whirling flames: Snegirev, A. Y. et al. International of Journal Heat and Mass Transfer,2004, 47, (10–11), 2523–2539

Liquid-to-air membrane energy exchangers (LAMEEs) allow simultaneous heat and moisture transfer between salt solution flows and airflows. These exchangers can be used as air dehumidifiers for supply air or liquid desiccant regenerators in liquid desiccant air conditioning systems while the membrane eliminates entrainment of liquid desiccant as aerosols in air streams. In this study, the heat and mass transfer performance of a LAMEE used as dehumidifier and regenerator is experimentally and analytically investigated to determine the influences of air and desiccant solution flow rates, inlet air temperature and humidity, and inlet desiccant solution temperature and concentration. Using the experimental data, the analytical model for the counter-cross-flow LAMEEs is quantitatively validated for sensible and latent effectiveness during air dehumidification process for the inlet conditions tested, while agreement is not good for the salt solution regeneration or de-watering process. This discrepancy may be caused by the crystallization of LiCl aqueous solution within the membrane pores near the solution side of the membrane during the regeneration tests. The data implies that both the moisture flux ratios and the proximity of the solution concentration to the saturation concentration play a role for moisture transfer blockage within the membrane when the data for latent effectiveness is significantly below the theoretical values. The influences of inlet air and solution parameters on the mass transfer performances of the LAMEE used as dehumidifier and regenerator are also compared with those of direct-contact liquid desiccant devices available in the literature.