Performance evaluation of hydrophilic organic polymer sorbents for desiccant air-conditioning applications

Abstract

The present study provides performance evaluation of two kinds of crosslinked hydrophilic organic polymer sorbents (PS-I and PS-II) for desiccant air-conditioning applications. In this regard, optimum temperature and humidity zones are established for various air-conditioning applications which include (i) humans’ thermal comfort, (ii) animals’ thermal comfort, and (iii) postharvest storage of fruits/vegetables. Honeycomb-like desiccant blocks composed of PS-I/PS-II are assumed for numerical simulation analysis. The numerical simulation model is programmed into MATLAB which utilizes the scientific relationships of adsorption isotherms, adsorption kinetics, isosteric heat of adsorption, and thermophysical properties for each sorbent. A particular desiccant air-conditioning system design is proposed, and numerical simulation has been conducted for the performance evaluation of PS-I and PS-II. According to the results, PS-I enables higher dehumidification than PS-II at low regeneration temperature (50℃) and cycle time of 60:90 min. It is because the PS-I possesses better water vapor sorption kinetics as compared to PS-II. Although the PS-II enabled higher steady-state adsorption amount but it could not influence the overall system performance. On the other hand, the optimum performance by the PS-II is limited to relatively long cycle time and higher regeneration temperature (≥80℃). It has been concluded that the PS-I is relatively better choice for desiccant air-conditioning, and consequently can be considered for various air-conditioning applications. Furthermore, effects of mass flow rate, isosteric heat of adsorption, regeneration temperature, and cycle time on air humidity ratio and air temperature profiles have been discussed in order to highlight the performance variability of desiccant air-conditioning system.

Energy-Efficient Air-Conditioning Systems for Nonhuman Applications

“…In addition, supplied air temperature and humidity from the AC unit is directly associated with the air-flow rates [3]. Consequently, the ideal temperature and humidity required for various animals is shown in Figure 1(b) [4,26]. It can be noticed that the animals require higher relative humidity in general as compared to human beings [3].…”

“…Therefore, low-cost and technically viable AC technology is the dire need for the food industry. From the discussion point of view, ideal temperature and humidity requirements for the storage of fruits and vegetables are compared on psychrometric chart as shown in Figure 3 [4]. The fundamental knowledge used in Figure 3 is obtained from the guidelines provided by the reference [34].…”

“…Referring to Figure 10(a), inlet and outlet air conditions of DAC can be simply expressed by Eqs. (18)- (25), while detailed DAC models can be found from references [4,53].…”

“…For example, cooling and humidification is required in summer season of Multan (Pakistan), whereas heating and humidification is required in dry winters of Fukuoka (Japan) [3]. Certainly, there could be numerous AC applications which may require specific conditions of T a and RH, for example, animals' AC [4], greenhouse AC [2,5], agricultural products' storage and preservation [6,7], and so on. The requirements of T a and RH vary dynamically with respect to time and may even vary from species to species [4].…”

“…Certainly, there could be numerous AC applications which may require specific conditions of T a and RH, for example, animals' AC [4], greenhouse AC [2,5], agricultural products' storage and preservation [6,7], and so on. The requirements of T a and RH vary dynamically with respect to time and may even vary from species to species [4]. On the other hand, the AC term is mostly associated with humans' thermal comfort as far as conventional literature and primary objectives are concerned [8,9].…”