Session: 08-14-03: Emerging Technologies in Solar Energy

Paper Number: 96152

96152 - Feasibility Study and Design of a Seawater Air-Conditioning System for a University Building in Fiji 

The demand for space cooling in Fiji is increasing rapidly due to a high infrastructure development rate. Climate change on the other hand is contributing to the problems as the earth’s surface temperature is increasing therefore making space cooling a necessity. The South Pacific countries have a reasonably constant temperature at the surface of the ocean and deep sea. SWAC is a combined solution to the problem of both space cooling and climate change through the use of renewable energy. In this work, a feasibility study and design of a SWAC system for the University of the South Pacific’s Marine Studies complex  is carried out. The feasibility study included the load calculations, the depth of seawater at which sufficient cold water is available for space cooling and the distance from shore to the depth of available cold water. The cooling load calculations were carried out using CAMEL software which came to be approximately 500 kW. Local bathymetry charts were studied and the depth at which the temperature of the seawater was about 6 degC was found to be 950 m. The distance from shore at which the cold water was available is approximately 11 km. The design phase of the system included the entire building’s supply and return duct system divided among 5 AHUs. The supply air quantities were extracted from CAMEL and used to size the diameters of the ducts. The length of the seawater suction pipeline was estimated using the depth and the distance to be around 12 km. The diameter of the seawater suction pipe was optimized using cost of pipe installation and pumping power to be 0.3 m, corresponding to a pumping power of 4.5 kW. A heat exchanger with a capacity of 500 kW, similar to the total cooling load of the building was selected to transfer heat between the seawater loop and the chilled water loop. The chilled water pumping power was calculated as a function of the location of the pump house and the respective AHUs. A 1:15 scaled down model of the building was constructed together with the supply duct, return duct  and 5 model AHUs. Various parameters such as temperature of chilled water, flow rate of chilled water and flow rate of air were altered to see the effect of cooling inside the building. Optimal design parameters were seen to be an airflow of 0.22m3/s at the AHU exit, cold water inlet temperature of 7°C and a cold-water flow rate of 15 L/min. A temperature of 23°C was achieved inside the building after 10 mins after running the system at the above-mentioned rates. The total cost for the implementation of the SWAC system for the Marine Studies complex was estimated to be $4.6 million and the payback period was estimated to be 7.5 yrs compared to a conventional split type cooling system.

Presenting Author: Mohammed Rafiuddin Ahmed The University of the South Pacific

Presenting Author Biography: Prof. Ahmed holds a Bachelor’s degree in Mechanical Engineering, Master’s degree in Fluids Engineering and a PhD degree also in Fluids Engineering (energy efficiency) from the prestigious IIT Bombay, that he earned in 1998. He has held full-time and visiting positions in Japan, New Zealand, India and South Korea apart from his current position of Professor of Mechanical Engineering at the University of the South Pacific. His areas of interest are Thermo-fluids and energy engineering. He has more than 20 years of teaching experience in these areas. He is also actively researching in these areas for well over 20 years and has more than 120 international publications with about half of them in reputed international journals. He was an invited speaker at a number of international conferences, a member of the International Advisory Boards/Technical Committees of the International Symposium on Fluid Machinery and Fluid Engineering, International Symposium on Low Carbon and Renewable Energy Technology, Asia-Pacific Forum on Renewable Energy (2011-2019) and the IAHR Symposium to be held in Beijing in October 2017. He was a member of the Organizing Committee for ASME International Mechanical Engineering Congress and Exposition (IMECE2013) held in San Diego, USA and also of the Asian Wave and Tidal Energy Conference Series (AWTEC2012, 2014, 2016 and 2018). He has received best-paper awards at international conferences. He is a reviewer for many reputed international journals. He was also a reviewer of the IPCC report on Renewable Energy Sources and Climate Change Mitigation. He is working on a number of projects in the areas of wind and ocean energies and has given invited lectures at a number of universities and research centres. He is the leader of the Renewable Energy Research Group at USP and has attracted lot of funding in the area of renewable energy. He is the Coordinator of the Mechanical Engineering programme at USP for a long time. He is a life member of the American Society of Mechanical Engineers (ASME) and a Senior Member of the American Institute of Aeronautics and Astronautics (AIAA).

Authors:

Muzammil Ali The University of the South Pacific
Reemal Prasad The University of the South Pacific
Mohammed Rafiuddin Ahmed The University of the South Pacific