摘要:

Irradiance was investigated at Nsugbe with a cadmium sulphide (CdS) photoresistor. It is observed that cadmium sulphide photoresistor with an efficiency of 7% corresponds to maximum average hourly irradiance of 65 W m−2if the CdS were 100% efficient. Comparison of results with the modified empirical equation of Rapp and Hodman showed reasonable agreement between recorded and theoretical results of hourly irradiance in W m−2.

ISSN:0142-5919    

DOI:10.1080/01425919208909786

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

This paper describes the results of a study of Si and thermopile solar irradiance sensors over a period of almost one year. The study centered around two main topics: 1) the method of calibrating them outdoors and 2) the accuracy of such devices relative to a selected thermopile as the reference. A new method for outdoor calibration of solar irradiance sensors is proposed for adoption as an international standard. It is concluded that Si sensors are good substitutes to the more expensive thermopile pyranometers for a continuous monitoring of solar irradiance. Based on this study, the paper also proposes basic construction criteria for the class of sensors for continuous outdoor use.

ISSN:0142-5919    

DOI:10.1080/01425919208909787

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

This paper presents the description and the performance curves of a natural draft solar fan that suits the ventilation requirements of greenhouses in hot climates. The developed solar fan utilizes the abundant sun energy (fan heating load) to induce upward air flow due to buoyancy forces and chimney thermal effect. The ventilated air is extracted into the greenhouse from outside through a wet pad, thus producing air cooling by means of evaporation. A back-up passive system is used for overnight and cloudy days. Different greenhouses - fan configurations and fan performance theoretical analysis are presented. The greenhouse ventilation air flow rate was found to depend upon the fan heating load, chimney height, greenhouse set temperature and ambient temperature. Computation results for a typical 3 m greenhouse height, 2000 m greenhouse ground area and 5 m chimney height indicated that the ventilation rate is 29 air volume change per hour AVCH (m = 11 kg/s), when the greenhouse is maintained at 25°C and the ambient temperature is 30°C. Reducing the ambient temperature to 20°C and 10°C increases the ventilation rates to 38 AVCH (m = 14.5 kg/s) and 44° AVCH (m = 17 kg/s) respectively. The present ventilation system is passive and therefore requires minimum maintenance, minimum operation skills, no electricity, and yet suits agricultural purposes in desert and remote areas.

ISSN:0142-5919    

DOI:10.1080/01425919208909788

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

Modern technology presently available for gasifying biomass is reviewed. The major demonstration projects and commercial plants are identified. The emphasis is on the larger units (≥5MWt), potentially suitable for electricity production in Western Europe. Important development items are identified and the ongoing research in Europe is briefly summarized.

ISSN:0142-5919    

DOI:10.1080/01425919208909789

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

The authors have proposed a generalisation of the J-CHART method [1] for a polyvalent modular drying system obtained by multiple simulation of thermal performance of two standard configurations: without recycling the air leaving the dryer, with 50% recycling of the air leaving the dryer and mixing with the air leaving the collectors.

ISSN:0142-5919    

DOI:10.1080/01425919208909790

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

In this communication, a transient analysis of a multi-effect active distillation system has been presented by taking the design and climatic parameters into account. An analytical expressions for the various water and glass temperatures, hourly yield and instantaneous thermal efficiency have been derived. The proposed system can also be used for second and third stage distillation. Numerical computation predicts that the daily yield increases with increase of number of effects (evaporating and condensing surfaces).

ISSN:0142-5919    

DOI:10.1080/01425919208909791

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor