Solar chimney—A passive strategy for natural ventilation

The need to put in place alternative energy policies stems from the awareness that fossil fuels are exhaustible and harmful to the environment. For this reason, during the last decades the scientific world has focused on systems able to use and convert renewable energy sources, particularly solar radiation. Nowadays, solar thermal collectors use solar energy to distribute low-cost domestic and industrial heating. In this review a comprehensive analysis of peer-reviewed journals and relevant papers on solar thermal collectors is provided. Descriptions of the different types of solar collectors are provided. Theoretical analyses, latest developments related to the functional elements, and hybrid systems have been considered throughout this analysis. Performance test methods for solar thermal collectors and standards are discussed. This cross-review aims to assist researchers, engineers and manufacturers in keeping them abreast of latest developments in the field of solar thermal collectors.

Latest advances on solar thermal collectors: A comprehensive review

Energy, exergy, economic and environmental (4E) analyses of flat-plate and V-groove solar air collectors based on aluminium and copper

Solar chimney as a reliable renewable energy system has attracted increasing attention from engineers to conquer the current energy crisis. The main challenge of designing a solar chimney is to optimize its performance with the lowest cost. Based on literature review, thirteen key influencing factors were obtained and classified into four groups, including configuration, installation conditions, material usage, and environment. Statistics of experimental studies showed that the overall tested range is still limited which suggests more future experiments. To enhance the performance, a solar chimney is suggested with possible high cavity and solar radiation, a cavity gap of 0.2–0.3 m, equal inlet and outlet, a height/gap ratio of around 10, an inclination angle of 45–60° (for roof solar chimney considering latitude), an appropriate opening of room, double/triple glazing, a 5 cm thick insulation wall, and a solar absorber with larger absorptivity and emissivity. These optimum values may not be applicable to all configurations as they are interdependent. Although external wind shows significant influence on solar chimney, solar chimney design can be undertaken without considering the effects from wind. This review will provide a useful technical guide for researchers and professionals regarding the optimum designs of solar chimney in buildings.

Determining the influencing factors on the performance of solar chimney in buildings

Effect of selective coating on thermal performance of flat plate solar air heaters

In this paper, a parametric study on the thermal performance of a solar air collector with a v-groove absorber has been investigated. In this single-cover collector, the air flowing in the channel formed by the v-groove absorber and the bottom plate—which is flat and insulated—is along the groove, aiming at enhanced heat transfer rate between the air and the absorber by increasing the heat transfer surface area, which is crucial to the improvement of thermal performance of a solar air collector. To quantify the achievable improvements with the v-groove absorber, a flat-plate solar air collector where both the absorbing plate and the bottom plate are flat, is also considered. The thermal performance of these two types of solar air collectors is analyzed and compared under various configurations and operating conditions. The results show that the v-groove collector has considerably superior thermal performance to the flat-plate collector. It is also found that to achieve better thermal performance, it is essential to; use a small size of the v-groove absorber for the v-groove absorber collector and to maintain a small gap between the absorber and the bottom plate for the flat-plate collector; to use selected coatings that have a very high absorptivity of solar radiation but a very small emissivity of thermal radiation on the absorber and glass cover; to
maintain an air mass flow rate above 0.1kg/m2s; and to operate the collectors with the inlet fluid temperature close to that of the ambient fluid.

A Parametric Study on the Thermal Performance of a Solar Air Collector with a V-Groove Absorber

Multipole theory analysis of a rectangular transmission line family

The related tank-type focus solar energy combined heat and power (CHP) system comprises: a sun focus reflection mirror (1) set on a rotation axis (9) fixed on (10), a heating water tank (2), a circulating pump (3) linked with (2) by the pipe (4), a heat and power composite receiver (5) linked with one end of (4), some electrodes (6) to output electric energy from (5), the sun light from sun (11), and a connection rod (8) supporting (5) on a ground frame (10). This invention is compact, high efficiency, and convenient to assemble and spread.

Slot light collection solar thermal power united supply compound system

The subregion solution of multipole theory(MT) is presented as a new approach for the analysis of propagation characteristics of a ridge waveguide family. The complicated field domain not satisfying the MT series expansion condition is treated as a combination of several simple field regions satisfying the MT series expansion condition, and the solution of the governing partial differential equation is represented by the generalized analytical MT formula. Representative computational examples including L-shaped, single-ridge, double-ridge, trapezoidal-ridge and quadruple-ridge waveguides are given to validate the theory and to demonstrate the accuracy and flexibility of the MT method.

Analysis of a ridge waveguide family based on subregion solution of multipole theory

The invention relates to a tank focus solar pv photo-thermal compound collector, belonging to the solar energy utilization technical field. The compound collector consists of a housing (4), a compound heat pipe (8) which is fixed with the housing (4) by a connecting screw (7), a solar cell (1) which is positioned on a bracket below the compound heat pipe (8), an insulating heat-conducting tape which is positioned on the solar cell (1), a glass cover board (3) which is positioned on the housing (4), a thermal insulation material (5) which is positioned between the housing (4) and the compound heat pipe (8), and an insulating strip (6) which is positioned between the upper part of the compound heat pipe (8) and the housing (4), wherein, the inner pipe wall of the compound heat pipe (8) is provided with fins (9) evenly and symmetrically. The tank focus solar PV photo-thermal compound collector can realize the combination of the utilization of PV/ photo-thermal of one collector part and has the advantages of high solar efficiency, novel structure, convenient manufacture and installation, thereby being widely applicable to tank focus solar PV/photo-thermal multiple-purpose systems.

Qinhong Zheng

Papers

A Parametric Study on the Thermal Performance of a Solar Air Collector with a V-Groove Absorber

Multipole theory analysis of a rectangular transmission line family

Slot light collection solar thermal power united supply compound system

Analysis of a ridge waveguide family based on subregion solution of multipole theory

Slot light- focused solar light voltage thermal compound heat collector