Effect of operating conditions on the performance of the bubble pump of absorption-diffusion refrigeration cycles

The mathematical model will be able to predict the operated condition (required tube diameters, heat input and submergence ratio….). That will result in a successful bubble pump design and hence a refrigeration unit. In the present work a one-dimensional two-fluid model of boiling mixing ammonia-water under constant heat flux is developed. The present model is used to predict the outlet liquid and vapor velocities and pumping ratio for different heat flux input to pump. The influence of operated conditions such as: ammonia fraction in inlet solution and tube diameter on the functioning of the bubble pump is presented and discussed. It was found that, the liquid velocity and pumping ratio increase with increasing heat flux, and then it decreases. Optimal heat flux depends namely on tube diameter variations. Vapour velocity increases linearly with increasing heat flux under designed conditions

Comparative Study for Evaluation of Mass Flow Rate for Simple Solar Still and Active with Heat Pump

In isolated and arid areas, especially in the almost Maghreb regions, the abundant solar radiation intensity along the year and the available brackish water resources are the two favorable conditions for using solar desalination technology to produce fresh water. The present study is based on the use of three groups of correlation, for evaluating mass transfer. Theoretical results are compared with those obtained experimentally for a Simple Solar Distiller (SSD) and a Simple Solar Distiller Hybrid with a Heat Pump (SSDHP) stills. Experimental results and those calculated by Lewis number correlation show good agreements. Results obtained by Dunkle, Kumar and Tiwari correlations are not satisfactory with the experimental ones. Theoretical results, as well as statistical analysis, are presented. The model with heat pump ( for two configurations (111) and (001) give more output compared with the model without heat pump ((000) and (110)). This results where agree for the use of the statistic results, the error it less with Lewis number as compared with the different correlation

A strategy to ensure the correct thickness of optical couplers in concentrating photovoltaic systems

Adding a dielectric Secondary Optical Element (SOE) to a Concentrating Photovoltaic (CPV) system provides several advantages. Besides increasing the concentration-acceptance angle product attainable by the system, a more uniform irradiance on the solar cell can also be achieved. The most common solution to glue the SOE and the solar cell consists in using an elastomer such as silicone. In this case, the silicone is acting both as an optical coupler to reduce Fresnel losses and as a mechanical bond. In this paper, we present a new approach to fix the thickness of the silicone in order to ensure a good adherence