Testing of solar cookers and evaluation of instrumentation error Ishan Purohit * Energy Environment Technology Division, The Energy and Resource Institute (TERI), India Habitat Center, Darbari Seth Block, New Delhi 110003, India article info Article history: Received 8 March 2008 Accepted 6 February 2010 Available online 25 March 2010 Keywords: Box type solar cooker Parabolic concentrator type solar cooker Instrumentation error Root-sum square method abstract Solar cooking technologies have large potential in developing countries. Many of the solar cookers (particularly box type and parabolic concentrating type solar cookers) have been commercialized in different parts of the world. An effective quality control is essential for a large-scale dissemination of solar thermal technologies on the products being offered by the industry to the end users. For this, there is a need to establish test procedures and methodologies for developing performance characteristic parameters, which could provide an equitable basis for comparison of performances of the products. A comprehensive review of various test procedures of solar cookers has been undertaken in this study. This study presents results of using various test procedures for characterizing box type and a family size parabolic concentrator solar cooker, based on detailed experimental investigations. The study is supported by a number of experiments carried at the location of New Delhi (latitude ¼ 28.56  N, longi- tude ¼ 77  E) under various climatic and operating conditions round the year. The overall error associated in the determination of performance parameters due to instrumentation has been estimated by using the root-sum square method. It has been estimated that instrumentation cause 1e5.5 percent error on the thermal performance parameters of solar cookers. The effect of instrumentation error has been evaluated maximum on second figure of merit, F 2 , optical efficiency factor, F 0 h o , and standardized cooking power P s . Ó 2010 Elsevier Ltd. All rights reserved. 1. Introduction Cooking with the sun is a potentially viable substitute for fuel- wood in food preparation in much of the developing world [1]. Several designs of solar cookers are available for domestic/ community cooking in developing countries [2]. Box type and parabolic concentrating solar cookers are commercially available in India. Evaluation of thermal performance of the solar cookers, as manufactured by the industry, assumes significance to enhance the users' confidence in it and also to provide an equitable basis for comparison of various models. In order to have a sustained growth of the solar energy technologies it is essential to have a proper mech- anism for characterizing the performance of these devices and systems under typical Indian climatic and operating conditions. Solar thermal devices hold a large potential for use in a variety of applications in developing countries [1e3]. There is a renewed interest in the design, development and testing of various types of solar cookers like box type [4e10], concentrator type [11,12] and oven type [13,14] around the globe in which the box type solar cooker has reached commercialization [15e17]. The solar cookers, mainly the box type and parabolic concentrator type solar cookers have been in use by individual families in urban and semi-urban areas [17]. In India, more than six million box type solar cookers have been propagated, largely under various schemes of the Ministry of New and Renewable Energy (MNRE) of the Government of India [17] which is far below from their respective potential [18]. Few prototypes of large solar cooking systems based employing low pressure steam generation through concentrating reflectors or parabolic dishes are also installed in various places of India for community and institutional cooking. India has world largest solar cooking plant [17,18]. A variety of reasons are attributed to the current low levels of dissemination of solar cookers in India as against their respective estimated potentials. Several of these attributes could, one way or the other, be related to the current status of development of the technology, its appropriateness and dissemination strategies adopted for their diffusion and deploy- ment [19e21]. In order to have a sustained growth of the solar thermal devices it is essential to have a proper mechanism for characterizing the performance under various climatic and oper- ating conditions. The need to evaluate a solar cooker and compare different designs calls for testing procedures and performance parameters which represent their respective thermal performance [22e24]. Vaishya et al. [25] proposed a test procedure for thermal perfor- mance evaluation of a box type solar cooker. On the basis of outdoor experiments, the maximum attainable temperature i.e. stagnation * Tel.: þ91 11 24682100; fax: þ91 11 24682145. E-mail address: ishanp@teri.res.in Contents lists available at ScienceDirect Renewable Energy journal homepage: www.elsevier.com/locate/renene 0960-1481/$ e see front matter Ó 2010 Elsevier Ltd. All rights reserved. doi:10.1016/j.renene.2010.02.006 Renewable Energy 35 (2010) 2053e2064