Performance of LiCl Impregnated Mesoporous Material Coating over Corrugated Heat Exchangers in a Solid Sorption Chiller

Abstract

The composite material made by impregnating 40 wt. % lithium chloride (LiCl) into the mesopores of a kind of natural porous rock (Wakkanai Siliceous Shale: WSS) micropowders (short for "WSS + 40 wt. % LiCl") had been developed previously, and can be regenerated below 100 • C with a cooling coefficient of performance (COP) of approximately 0.3 when adopted as a sorbent in a sorption cooler. In this study, experiments have been carried out on an intermittent solid sorption chiller with the WSS + 40 wt. % LiCl coating over two aluminum corrugated heat exchangers. Based on the experimental condition (regeneration temperature of 80 • C, condensation temperature of 30 • C in the desorption process; sorption temperature of 30 • C and evaporation temperature of 12 • C in the sorption process), the water sorption amount changes from 20 wt. % to 70 wt. % in one sorption cooling cycle. Moreover, a specific cooling power (SCP) of 86 W/kg, a volumetric specific cooling power (VSCP) of 42 W/dm 3 , and a specific sorption power of 170 W/kg can be achieved with a total sorption and desorption time of 20 min. The obtained cooling COP is approximately 0.16.Energies 2018, 11, 1565 2 of 15 the condenser to release heat. For the opposite process, cooling energy can be obtained in an evaporator because of water evaporation, and the evaporated water vapor binds to the sorbent during the sorption process [15]. Several novel porous solids with water as refrigerant are being researched in sorption heating and cooling systems: silica gel, FAM-01 and FAM-02 developed by Mitsubishi Plastics Ltd. (Tokyo, Japan), metal-organic frameworks (MOFs), and various composite sorbents [16]. Among these sorbents, composite sorbents are considered to be promising to enhance the efficiency of the sorption cooling and heating system by means of a target-oriented design of the sorbent specified for a particular cycle. Composites with two components can offer the opportunity for nano-tailoring the sorption properties by varying the confined salt chemical nature and content, porous structure of host matrix, and synthesis conditions [16,17].Two basic configurations for the composite sorbents-water working pairs were described in the literatures; namely, (1) packed bed sorbent contacting with the heat transfer surface, and (2) sorbent coating on the heat exchanger surface. For the packed bed sorbent cooling systems, Restuccia et al. [6,18] developed an adsorptive cooling system with packed SWS-1L (mesoporous silica gel impregnated with CaCl 2 ) inside a high-efficiency heat exchanger. A mean SCP of 20-40 W/kg of adsorbent and a cooling COP of 0.4-0.6 were obtained when the T re was 95 • C, T con was 35 • C, and T ev was 10 • C. Freni et al. [19] tested the performance of a packed bed sorption chiller using SWS-8L (silica modified by Ca(NO 3 ) 2 ). At the operation condition of T ev = 15 • C, T con = 30 • C, and T re = 90-95 • C, the cooling COP increased from 0.28 to 0.41, while the SCP decreased from 389 W/kg to 190 W/kg when the cycle time changed from 8 min ...

Experimental Determination and Thermodynamic Model of Solid–Liquid Equilibria in the Ternary System (LiCl + CaCl2 + H2O) at 273.15 K

“…Because of their excellent characteristics, lithium and calcium resources play a significant role in the fields of battery materials, food processing, and medicine . For example, in the medical field, Li 2 CO 3 was widely used to treat the mental disease, while CaCl 2 was an effective medicine to adjust the concentration of Ca 2+ in the blood.…”