EXPERIMENTAL ANALYSIS OF A VELOCITY FIELD USING VARIABLE CHIMNEY DIAMETER FOR SOLAR UPDRAFT TOWER Neeraj Mehla Department of Mechanical Engineering, National Institute of Technology, Hamirpur, Himachal Pradesh-177055.India Rahul Makade Department of Mechanical Engineering, National Institute of Technology, Hamirpur, Himachal Pradesh-177055.India N.S.Thakur Centre For Excellence in Energy & Environment National Institute of Technology, Hamirpur, Himachal Pradesh-177055.India Abstract A solar updraft tower consists of an air collector 1.4 m in diameter and 80 cm tall chimney was set up in NIT Hamirpur, Himachal-Pradesh, India. The objective of the study was to investigate the variation of velocity with essential geometric parameter of the system. The solar updraft tower system consists of three essential elements- collector, chimney height and wind turbine. The output power of a system is depended on the input velocity to the wind turbine. Turbine inlet velocity (V) is the function of five parameter of the solar updraft tower systems such as collector diameter (D c ), roof glass angle (β), entrance height (h), tower's height (H t ), tower's diameter (D), out of which variable roof angle and the chimney height is analysis. It was found that the solar chimney diameter of 8 cm is having the maximum velocity for the constructed setup, and the ratio of chimney diameter to chimney height was found to be 0.1. 1. Introduction In India Solar chimneys have been traditionally used in agriculture applications like drying of crops, grains, fruits or wood. Natural ventilation in buildings is another popular application of solar chimney. Due to exponential increase in energy cost, a strong demand for renewable energy is raised. Scientists are exploring different techniques focusing on different aspects including minimizing operational costs, simplifying and lowering maintenance cost, minimizing the use of toxic materials due to health and environmental concerns, and increasing reliability. The solar chimney is one of the techniques that have a strong potential as a green source of energy, which as many advantages and has huge potential in energy generation including renewable eco- friendly energy, zero pollution and availability. Therefore it has a broad range of applications and can contribute substantially to our future energy needs. India's 2007 total fossil-fuel CO 2 emissions rose 7.2% over the 2006 level to nearly 440 million metric tons of carbon. From 1950 to 2007, India experienced dramatic growth in fossil-fuel CO 2 emissions averaging 5.7% per year and becoming the world's third largest fossil-fuel CO 2 -emitting country. Neeraj Mehla et al. / International Journal of Engineering Science and Technology (IJEST) ISSN : 0975-5462 Vol. 3 No. 4 Apr 2011 3167