Rabah Boukhanouf

Theoretical and Experimental Investigation of a Novel Hybrid Heat-Pipe Solar Collector

Abstract This article describes a novel flat plate heat-pipe solar collector, namely, the hybrid heat-pipe solar collector. An analytical model has been developed to calculate the collector efficiency as well as simulate the heat transfer processes occurring in the collector. The effects of heat pipes/absorber, top cover, flue gas channel geometry, and flue gas temperature and flow rate, on the collector efficiency were investigated based on three modes of operation, i.e., solar only operation, solar/exhaust gas combined, and solar, exhaust gas and boiler combined. Experimental testing of the collector was also carried out for each of these modes of operation under real climatic conditions. The results were used to estimate the efficiency of the collector and determine the relation between the efficiency and general external parameter. The modeling and experimental results were compared and a correlation factor was used to modify the theoretical predictions. It was found that the efficiency of the collector was increased by about 20–30% compared to a conventional flat-plate heat pipe solar collector.

Investigation of an Evaporative Cooler for Buildings in Hot and Dry Climates

The paper presents a computer model and experimental results of a sub-wet bulb temperature evaporative cooling system for space cooling in buildings in hot and dry climates. The cooler uses porous ceramic materials as the wet media for water evaporation. Under selected test conditions of airflow dry bulb temperature of up to 45 o C and relative humidity of up to 50%, it was found that the supply air could be cooled to below the wet bulb temperature with a maximum cooling capacity of 280 W/m 2 of the wet ceramic surface area. It was also shown that the overall wet bulb effectiveness is greater than unity. This performance would make the system a potential alternative to conventional mechanical air conditioning systems in hot and dry regions.

Simulation and Experimental Investigation of Thermal Performance of a Miniature Flat Plate Heat Pipe

This paper presents the results of a CFD analysis and experimental tests of two identical miniature flat plate heat pipes (FPHP) using sintered and screen mesh wicks and a comparative analysis and measurement of two solid copper base plates 1 mm and 3 mm thick. It was shown that the design of the miniature FPHP with sintered wick would achieve the specific temperature gradients threshold for heat dissipation rates of up to 80 W. The experimental results also revealed that for localised heat sources of up to 40 W, a solid copper base plate 3 mm thick would have comparable heat transfer performances to that of the sintered wick FPHP. In addition, a marginal effect on the thermal performance of the sintered wick FPHP was recorded when its orientation was held at 0°, 90°, and 180° and for heat dissipation rates ranging from 0 to 100 W.

Theoretical and Experimental Investigation of a Two-Bed Adsorption System Using a Novel Adsorber Configuration

To improve the performance of an adsorption system for cooling applications, a novel integrated adsober/evaporator configuration made of a bellows structure was described. A two-bed adsorption system arrangement using the bellows adsorber and zeolite 13X/water working-pair and related mathematical analysis was also presented. Results of computer modelling and experimental tests of various operating and performance parameters of the system including operating temperature and pressure in the adsorbent bed, mass transfer, COP and SCC were discussed.

Approach for Integrating Indirect Evaporative Cooling System into Contemporary Architecture

Nowadays, the knowledge of building ecology focuses on energy efficiency and how to integrate environmental and climatic parameters into HVAC and thus enhances space qualities such as comfort ability. The aim of this paper is to demonstrate the rule of Indirect Evaporative Cooling systems in sustainability of contemporary architecture in hotarid and hot-humid climate. An approach for integrating a novel Sub-Wet Bulb Temperature Evaporative cooler into contemporary architecture is presented. The system uses porous clay materials, as wet media, embedded with heat pipes heat exchangers, the supply air and working air flows were staged in separate ducts and in counter flow direction. Modelling and experimental results show that supply air would be cooled to below wet bulb temperature achieving a considerable cooling capacity and effectiveness. This performance would make the system a potential alternative to conventional mechanical air conditioning systems in buildings.

An experimental investigation on the effect of ferrofluids on the efficiency of novel parabolic trough solar collector under laminar flow conditions

ABSTRACT The paper is related to the use of magnetic nanofluids (ferrofluids) in a direct absorption solar parabolic trough collector, which enhances thermal efficiency compared to conventional solar collectors. By applying the right magnetic intensity and magnetic field direction, the thermal conductivity of the fluid increased higher than typical nanofluids. Moreover, the ferrofluids exhibit excellent optical properties. The external magnetic source is installed to alter the thermo-physical properties of the fluid, and the absorber tube does not have selective surface allowing ferrofluids to absorb the incoming solar irradiance directly. In this paper, an experimental investigation of the performance of small scale direct absorption solar collector using ferrofluids as an absorber was conducted. Nanoparticle concentrations of 0.05 vol% at the operational temperatures between 19°C and 40°C were used in the current study. The results show that using ferrofluids as a heat transfer fluid increases the efficiency of solar collectors. In the presence of the external magnetic field, the solar collector efficiency increases to the maximum, 25% higher than the conventional parabolic trough. At higher temperatures, the ferrofluids show much better efficiency than conventional heat transfer fluid. The study indicated that nanofluids, even of low-content, have good absorption of solar radiation, and can improve the outlet temperatures and system efficiencies. The study shows the potential of using ferrofluids in the direct absorption solar collector.

Small combined heat and power (CHP) systems for commercial buildings and institutions

Abstract: Small-scale CHP has a huge potential to deliver energy savings and be an effective carbon mitigation strategy in commercial buildings and institutions. This chapter starts with a brief discussion about energy requirements, trends, and the regulatory frameworks driving energy efficiency in these types of buildings. Then details on technical and operational characteristics of small-scale CHP technology are given with emphasis on implementation in different types of buildings. Finally, future prospects and ways to support the technology are discussed.