Experimental Heat Transfer Research in Enhanced Flat-Plate Solar Collectors

Abstract

Enhancement techniques can be applied to flat-plate liquid solar collectors towards more compact and efficient designs. Tube-side enhancement passive techniques can consist of adding additional devices which are incorporated into a smooth round tube (twisted tapes, wire coils), modifying the surface of a s mooth tube (corrugated and dimpled tubes) or making special tube geometries (internally finned tubes). For the typical operating flow rates in flat-plate solar collectors, the most suitable technique is inserted devices. Based on previous studies from the authors, wire coils were selected for enhancing heat transfer. This type of inserted device provides better results in laminar, transitional and low turbulence fluid flow regimes. To test the enhanced solar collector and compare with a standard one, an experimental side-by-side solar collector test bed was designed and constructed. The testing set up was fully designed following the requirements of EN12975-2 and allow us to accomplish performance tests under the same operating conditions (mass flow rate, inlet fluid temperature and weather conditions). In this work the preliminary results obtained are presented and the standardized efficiency curve is shown for both tested solar collectors. A relevant improvement of the efficiency has been reported and quantified through the useful power ratio between enhanced and standard solar collectors.

Experimental analysis of a solar water heater with a thermosiphone for domestic applications in the south-east of kazakhstan

“…In [9] is studied the characteristics of heat transfer and flow of a device for collecting solar energy using CFD modeling. In the article [10] is developed and investigated the effect of using coils of wires in absorber tubes to improve heat transfer and absorption of solar energy. In the article [11] was compared the efficiency and heat transfer to the solar collector.…”

Thermal performance analysis conical solar water heater

“…Potthuru R P et al [12] compared the performance fixed flat plate water heater with that of the heater with tracking by conducting experiments. Herrero Martin et al [13] developed an experimental side by side solar collector test under the requirement of EN12975-2. Taherian et al [14] analyzed the performance of the shell and tube HX external to the storage tank, in which fluid flow was induced by natural convection.…”

Numerical and experimental investigation of a thermosiphon solar water heater system thermal performance used in domestic applications

“…Furthermore, the thermal performance enhancement of a solar collector with a relative twisted ratio of the twisted tape = 2.5 m and 4 m is higher by 1.07% and 9.29%, respectively, than the conventional collector. The flat plate collector thermal performance was experimentally conducted by Herrero Martin et al 10 The impact of usage wires coils in the absorber tubes to enhance heat transmission and solar absorption has been examined. They have indicated that the efficiency increases with wire coils insert as compare with the standard collector.…”