Sunshine from a cloudless sky, as we have experienced it these past days, provides the ideal conditions for a Concentrating Solar Power plant, CSP. At DTU Mechanical Engineering, PhD student Anish Modi is at the moment working on improvements of CSP plants, a technology different from the more known solar cells.
There is more to solar energy than the more known solar cells, PV or photovoltaic cells. CSP, or Concentrating Solar Power, is a different technology that uses mirrors for concentrating solar radiation to heat water. The heated water can then be used for generating electricity, or for district heating as the CSP plant in Thisted, the first plant of that kind in Denmark. CSP plants can collect the solar energy reflected from the mirrors in different ways and convert it to heat. The electricity is produced by a conventional steam turbine cycle, when a fluid is evaporated and drives a steam turbine. Anish Modi is aiming at an improvement of the efficiency of the CSP plant by using a mixture of ammonia and water, instead of pure water.
Anish Modi, who started as a PhD student at the Section of Thermal Energy, DTU Mechanical Engineering, in September 2012, describes the status of his project:
“My work is related to the study of the CSP plants using ammonia-water mixtures as the working fluid, or as a part of operation in the power cycle in some other manner. Until now, we have done a preliminary feasibility study to assess the benefits of using ammonia-water mixtures instead of pure water in the CSP plants. The next step in the project is to do a detailed thermodynamic analysis, and then a thermo-economic evaluation of using ammonia-water mixtures in the CSP plant power cycles.”
The principle of a CSP plant. Illustration from EERE, Energy Efficiency and Renewable Energy, U.S. Department of Energy.
In his research, Anish Modi is investigating the possibility of using an ammonia-water mixture instead of water: “Hypothetically, an ammonia-water mixture has the potential to improve the heat transfer process in heat exchangers”, tells Anish Modi, “especially if a phase change is involved, e.g., changing from liquid to vapor, or vice versa. However, the use of an ammonia-water mixture in a high temperature CSP plant has not been studied previously. Therefore, it’s our task to find out if it is in fact beneficial to use an ammonia-water mixture, or if it’s better to go the conventional way by using pure-water. At the end of my PhD, we hope to have a sound answer to this question!”
Anish Modi has also submitted a paper regarding the preliminary results of the research to the Solar World Congress 2013 which takes place in November in Cancún, Mexico.
Photo: Colourbox.