The current challenges on different types of cooling systems were reviewed. The adsorption cooling system is believed to be able to solve the problems of energy shortage and environmental pollution.

Various simulations were conducted in aid of system design, operation cycle study and performance prediction of the newly developed composite adsorbents. The composite adsorbents synthesized from carbon nanotube, zeolite 13X and calcium chloride (CaCl₂) were investigated for applications in adsorption cooling systems. Detailed finite differential numerical simulation was conducted to study the performance of the adsorption cooling system. This simulation model gave clear figures to evaluate the performance of the adsorption cooling system and suggested useful method to improve the design...[ Read more ]

The current challenges on different types of cooling systems were reviewed. The adsorption cooling system is believed to be able to solve the problems of energy shortage and environmental pollution.

Various simulations were conducted in aid of system design, operation cycle study and performance prediction of the newly developed composite adsorbents. The composite adsorbents synthesized from carbon nanotube, zeolite 13X and calcium chloride (CaCl₂) were investigated for applications in adsorption cooling systems. Detailed finite differential numerical simulation was conducted to study the performance of the adsorption cooling system. This simulation model gave clear figures to evaluate the performance of the adsorption cooling system and suggested useful method to improve the design of the adsorber. A system simulation was conducted to investigate the effect of heat recovery, mass recovery, pre-heating and pre-cooling cycles and their combinations on the system performance of a double-bed adsorption cooling system.

A prototype of adsorption cooling was also built to obtain the real operation data using the zeolite 13X/CaCl₂ composite adsorbent. The operation data was also used to verify the simulation result. Among different operation cycles, mass recovery together with the pre-heating & pre-cooling cycle is preferred. It is also found that the specific cooling power (SCP) value when using the composite adsorbent is about 530% higher than that of the silica gel adsorbent when a chilled water inlet temperature of 8°C is required.

In order to theoretically predict the effective stagnant thermal conductivity of the composite adsorbents, the modified area-contact model was constructed. With smaller deviation compared to the area contact model, the modified area contact model is believed to be applicable to predict the effective stagnant thermal conductivity of a surface coated porous material. The synthesis procedure and material properties of the composite adsorbents were also discussed. It can be concluded that the addition of multi-walled carbon nanotube (MWCNT) does not have noticeable drawback on adsorption capacity and can improve the effective thermal conductivity of the composite adsorbent. A finite element method (FEM) simulation model was built to analyse the performance of an adsorber with different adsorbents. The SCP of the adsorber using MWCNT embedded 13X/CaCl₂ adsorbent was improved by 6.5 times to 1113.4 W/kg comparing to zeolite 13X. The total cooling power was largely enhanced by 13.4 times to 1783.2 W. By comparing to zeolite 13X/CaCl₂, simply adding the MWCNT can improve the adsorber performance by more than 20% in terms of COP and SCP. This shows that this MWCNT embedded zeolite 13X/CaCl₂ composite adsorbent is a good candidate to be used in adsorption cooling system.