Hind Saidani-Scott

Analysis of a Finned Heat Exchanger Working in an Adsorption Refrigeration System Using Zeolite and Methanol

A new refrigeration system that uses a specially designed finned plate heat exchanger and works with zeolite and methanol is proposed. The integration of heat transfer and adsorption via a finned surface coated with zeolite CBV 901 and the use of a connected, twin active bed system to enable heat recuperation are novel features. The thermophysical properties of zeolite and methanol were first studied with the intention of designing a high performance heat exchanger (generator) for the adsorption refrigeration system. Here, the major problem is related to poor conductivity at the interface between the heat exchanger and the zeolite. The adsorbent must be heated (desorption phase) and then cooled (adsorption phase) back to ambient temperature in order to complete a thermodynamic cycle. To manufacture a sufficiently small system, there must be high rates of heat transfer in and out of the adsorbent. Therefore, the surface of the heat exchanger is finned in order to increase the heat transfer area (the fins are coated with 2 mm layer of specially prepared zeolite paste). The following characteristics were estimated from initial calculation: heating temperature, 120°C; outside tube temperature, 119.6°C; middle fin temperature, 117°C; and coated layer of zeolite paste temperature, 115.3°C. The mathematical code developed to calculate the effects of operating conditions and the Coefficient of Performance (COP) was presented at HPC 2001 in Paris. It is based on the Dubinin-Astakhov equation and thermodynamic analyses. The results obtained shows that 0.535 is the COP for a single bed and 0.925 for a double bed.

Experimental Study of Water Filtering Using Textiles as in Traditional Methods

This paper presents experimental results following a feasibility study into the uses of textiles for water filtration and purification. This project emanated from another project called ‘Aquapol’ [1], sponsored by the EU [2], which looked at reduction of infant diseases by the use of clean filtered water. Due to the high cost and maintenance of manufactured filters used in the Aquapol project, it was decided to look at the traditional methods used locally and try and design a water filter made from simple non expensive materials. Various textile materials have been tested for water filtration particulate dealing with the simulation of traditional materials used in Africa and Asia (Like Shesh in North Africa and Sari in India). Some ‘modern’ materials (like Denim, curtain shower) have also been tested to see if their filtration capability is better or worst than the traditional ones. The results obtained showed that textiles were very efficient in reducing particles size transportation and could be used for filtering and pre-filtering. However, storage conditions and basic hygiene are still the most important factors for disease reduction