Parametric Study of to Design an Earth to Air Heat Exchanger with Experimental Validation

Geothermal energy uses an air ground exchanger to cool buildings with minimum of energy. The outlet air coming from this exchanger can be directly used for space cooling if its temperature is low enough. In this study we try to evaluate the profile of ground temperature to decide of the depth to bury the exchanger. Through modeling and experimentation, we try to evaluate the performance of a horizontal pipe used for cooling, for this finite differential method which consists on dividing the length of the exchanger on multiple equal segments and by the knowledge of initial and boundary conditions the profile of the air temperature is that carry out. The authors conclude that many parameters influence the performance of earth to air exchanger such as the nature of the ground, the ground depth diameter of the duct and the throughput flow

Multiple solutions for flow mode−transition in an inclined cavity generated by natural convection

An investigation of natural convection in a rectangular cavity (AR = 4) filled with air (Pr = 0.71) heated from the side with adiabatic horizontal walls is carried out numerically. To describe the flow regime, we propose a description of the influence of the angle of inclination and Rayleigh number on the flow patterns likely to develop in this configuration. The numerical analysis of the governing equations of the problem is based on finite volume method with non-staggered grids arrangement and is solved through the iterative SIMPLEC algorithm. Results indicate that the angle of inclination has a significant effect on flow mode transition. The existence of multi-steady solutions closely depends on the value of the Rayleigh number. For that the Hysteresis phenomenon (multi−steady solutions) for Ra ≥ 2000 are demonstrated and parameter maps of Ra vs. φ are proposed

Collector Efficiency by Single Pass of Solar Air Heaters with and without Using Fins

This paper presents the study of heat transfer in a solar air heater by using new design of solar collector. The collector efficiency in a single pass of solar air heater without, and with using fins attached under the absorbing plate has been investigated experimentally. Due to the adding the fins inferior an absorber plate, the desirable effect of increasing the heat transfer coefficient compensates for the undesirable effect of decreasing the driving force (temperature difference) of heat transfer, while the attached fins provide an enlarged heat transfer area. In this study, the absorbing plate of solar collector is attached with fins for further improved performance. The improvements of collector efficiencies in the single pass solar air heaters with, and without fins attached; increase with increasing the mass flow rate, especially for operating at lower air flow rate. Experiments were performed for two air mass flow rates of 0.012 and 0.016 kg/s. Moreover; the maximum efficiency obtained for the 0.012 and 0.016 kg/s with, and without fins were 40.02, 51.50% and 34.92, 43.94% respectively. A comparison of the results of the mass flow rates by solar collector with, and without fins shows a substantial enhancement in the thermal efficiency

Applicability of solar desiccant cooling systems in Algerian Sahara: Experimental investigation of flat plate collectors

The increasing interest in the development of solar cooling technologies to their various economic and impressive environmental benefits, conducted us to study the feasibility of solar desiccant cooling systems in Algerian Sahara, particularly in the region of Biskra. Thus, we present in this paper, the results of an experimental investigation of solar flat plate collectors (FPCs) to test and estimate their heat regeneration capacity for solid desiccant cooling applications. The applicability of both Pennington and Dunkle cycles taking into account the effects of some parameters such as outdoor humidity and temperature and hot air temperature required to regenerate the desiccant wheel have been studied. From the psychrometric analysis, it was found that the Dunkle cycle is suitable in warm and semiarid climate. In addition, this study has allowed us to show that the temperature achieved by the flat plate solar air heaters in a large band of air flow rate can satisfy the energy needs for the dehumidification in desiccant cooling systems. Hot water produced by the solar water heaters and the stored one are in the operating temperature gap of the system (50-80 °C)

The Air Solar Collectors: Introduction of Chicanes to Favour the Heat Transfer and Temperature in the Air Stream Dynamics

The thermal performance of a single pass solar air heater with chicanes attached was investigated numerically using a 2D model of solar air stream dynamics collectors where the turbulence standard (k-ε) model has been implemented. The chicane is formed with two parts: the first is perpendicular to the air flow and the second part is titled (α), they are mounted in successive rows, oriented perpendicular to the air flow and soldered to the back plate. The predicted results are validated by comparing with the literatures semi-empirical and experimental data and shown a reasonable agreement. Effects of relevant parameters as the (Reynolds number, chicanes upper parts tilts angles and air mass flow rates) on the heat transfer coefficient and temperature development are discussed. It is apparent that the turbulence created by the chicanes resulting in greater increase in heat transfer inside the air stream dynamics

The Air Solar Collectors: Introduction of Chicanes to Favour the Heat Transfer and Temperature in the Air Stream Dynamics

The thermal performance of a single pass solar air heater with chicanes attached was investigated numerically using a 2D model of solar air stream dynamics collectors where the turbulence standard (k-ε) model has been implemented. The chicane is formed with two parts: the first is perpendicular to the air flow and the second part is titled (α), they are mounted in successive rows, oriented perpendicular to the air flow and soldered to the back plate. The predicted results are validated by comparing with the literatures semi-empirical and experimental data and shown a reasonable agreement. Effects of relevant parameters as the (Reynolds number, chicanes upper parts tilts angles and air mass flow rates) on the heat transfer coefficient and temperature development are discussed. It is apparent that the turbulence created by the chicanes resulting in greater increase in heat transfer inside the air stream dynamics

Heat transfer and energy analysis of a solar air collector with smooth plate

The heat transfer and thermal performance of a single pass solar air heater a smooth plate was investigated experimentally. In the present paper, energy and heat transfer analysis of a solar air collector with smooth plate, this technique is used to determine the optimal thermal performance of flat plate solar air heater by considering the different system and operating parameters to obtain maximum thermal performance. Thermal performance is obtained for different mass flow rate varying in the array 0.0108–0.0202 kg/s with five values, solar intensity; tilt angle and ambient temperature. We discuss the thermal behavior of this type of collector with new design and with my proper construction. An experimental study was carried out on a prototype installed on the experimental tests platform within the University of Biskra in the Algeria. The effects of air mass flow rate, emissivity of channel plates and wind heat transfer coefficient on the accuracy of the criterion are also investigated

Study of Methods for Drying Dates; Review the Traditional Drying Methods in the Region of Touat Wilaya of Adrar-Algeria

AbstractTOUAT region is one of the most productive areas in Algeria dates. The date is a fruit rich in vitamins and fiber. Many varieties are well suited and very productive part of the surplus production is processed into dried dates. Different industrial drying methods are used as a drying oven or dryer. In the region of TOUAT, wilaya of Adrar, we practice sun drying in the open air for a period of 10 to 15 days, the fruit is dehydrated, but the quality is very poor compared to industrial drying. TOUAT region should benefit from small structures to transform the dry date fruit to include the surplus and help the social and economic development of the region

Experimental study of heat transfer and thermal performance with longitudinal fins of solar air heater

The thermal performance of a single pass solar air heater with five fins attached was investigated experimentally. Longitudinal fins were used inferior the absorber plate to increase the heat exchange and render the flow fluid in the channel uniform. The effect of mass flow rate of air on the outlet temperature, the heat transfer in the thickness of the solar collector, and the thermal efficiency were studied. Experiments were performed for two air mass flow rates of 0.012 and 0.016 kg s−1. Moreover, the maximum efficiency values obtained for the 0.012 and 0.016 kg s−1 with and without fins were 40.02%, 51.50% and 34.92%, 43.94%, respectively. A comparison of the results of the mass flow rates by solar collector with and without fins shows a substantial enhancement in the thermal efficiency

Experimental Study of Heat Transfer and an Effect the Tilt Angle with Variation of the Mass Flow Rates on the Solar Air Heater

Abstract-in this study we have been indicated an effect of tilt angle and the mass flow rates onto the thermal performance of a single pass solar air heater will be investigated experimentally. The effects of mass flow rate of air on the outlet temperature, the heat transfer in a solar collector and thermal efficiency were studied. Experiments were performed for range of air mass flow rates from 0.0078 to 0.0166 kg/s., Moreover; the maximum efficiency was obtained at the difference's mass flow rates. The maximum efficiency obtained for the 0.0078, 0.0093, 0.0125 and 0.0166 kg/s were 47.82%, 37.50%, 31% and 26% respectively. Comparison of the results as an effect the mass flow rates by solar collectors and the tilt angle a substantial enhancement in the thermal efficiency. The optimal tilt angles for the outlet temperature were between 20 and 30°