A. Mani

Performance comparison of vapour jet refrigeration system with environment friendly working fluids

A computer simulation of a vapour jet refrigeration system is carried out using a one-dimensional model based on mass, momentum and energy balances. The simulated performance of the system is in good agreement with the available experimental performance from the literature. A comparison of system performance is carried out for the same ejector geometry using the environmentally friendly working fluids R123, R134a, R152a and R717 (ammonia). The results suggest that, for different boiler temperatures, the entrainment ratio and the system efficiency (COP) depend mainly on the ejector geometry and the compression ratio.

Comparison between simulated and experimental performance of an open solar flat plate collector for treating tannery effluent

In this paper, comparison between theoretical and experimental analysis of an open type flat collector for tannery effluent treatment is presented. Effect of the parameters like insolation, wind speed, relative humidity, mass flow rate and salt concentration on the evaporation rate of water in the effluent is studied. An open type fibre reinforced plastic (FRP) flat plate solar collector is used for experimentation. The evaporation rate increases for increase in insolation, wind speed and mass flow rate and decrease in relative humidity and concentration.

Experiments on a bubble absorber

Experiments are carried out on a bubble absorber, operating as part of a vapour absorption refrigeration system working with HCFC22-DMF to obtain heat and mass transfer and pressure drop data. The results are evaluated to obtain the dependence of absorption process on different parameters. Experimental data are compared with the numerical correlation relating Sherwood number, Reynolds number, Schmidt number and length to diameter ratio developed earlier by the authors. Also the experimental pressure drop is compared with the pressure drop obtained from other well known classical correlations and the numerical model.

Experimental studies on thermal spray-coated horizontal tubes for falling film evaporation in multi-effect desalination system

AbstractMulti-effect distillation is an important principle in desalination technology, in which the thin film evaporation of sea water takes place at the outer surface of bundle of tubes, normally arranged in horizontal. Heat of condensation inside the tube is transferred to the falling water film by conduction, thereafter convective evaporation of film takes place. Heat transfer on the outside is unpredictable due to the uncertainty in nature of film, film thickness, film dryout, etc. and film coefficient is considerably less compared to inside. Thermal spray coating on metallic surface with molten metal particles create porous surface which enhances heat transfer due to higher turbulence and nucleation sites, if sufficient temperature difference available. This paper discusses the experimental studies carried out on a 3 × 5 bundle of 25.4 mm ∅ Al horizontal tubes with thermal spray coating of aluminum. Influences on temperature profile, heat transfer coefficient, mass evaporation, etc. are studied. A c...

Analysis of forced convective evaporation system for tannery effluent (soak liquor)

The objective of this work is to analyze a system for evaporating the water in tannery effluent (soak liquor). This system is designed based on the principle of forced convective evaporation. Soak liquor is made to flow as a thin film and air is drawn against the falling liquor film. This facilitates the direct contact heat and mass transfer between liquor and air. The system is modeled by applying the energy and mass balance. A parametric study has been carried out to find out the effect of operating parameters on the rate of evaporation. An experimental setup has been constructed and experiments have been conducted which prove the viability of the system. Theoretical performance matches closely with that of experiments. It is shown that the proposed forced convective evaporation system is better than existing methods of evaporation of tannery effluent in terms of evaporation rate as well as area requirement.

Desalination using spray tower and vapour compression refrigeration system

A desalination system using a spray tower and Vapour Compression Refrigeration (VCR) system is proposed for obtaining fresh water from brackish water. In the spray tower, simultaneous heat and mass transfer take place between the brackish water and air, which results in the evaporation of the brackish water and humidification of the air. Fresh water is obtained from the humidified air by condensing the water vapour using a VCR system. Parametric studies were carried out to study the effect of various operational parameters on the fresh water production rate.