ASSESSMENT OF THE PERFORMANCE OF OTEC HEAT EXCHANGER

Abstract

The performance assessment of OTEC heat exchanger has been conducted. The data was sourced from the World Seawater Temperature for the surface sweater temperature and the map of Nigeria coastal depth in order to ascertain the deep seawater temperature. A reference surface seawater temperature of 270C and 60C for colder deep seawater temperature with corresponding pressures of 9.78bar and 6.0bar respectively. Simulations were performed utilizing MATLAB software, with input conditions including seawater surface temperatures, pressures, mass flow rates, and cooling seawater temperatures. The key performance indicators were analyzed as follows: a mass flow rate of 1.694 x 103m3/s, heat rejected at the condenser of 2.01 x103kJ, an evaporator heat transfer area of 2.2702 x 106m2, and 42,412 tubes in the condenser and 70,148 tubes in the evaporator. OTEC systems need an extensive number of long tubes to achieve the necessary heat transfer surface area. These tubes make up some of the largest components of the system. The substantial number of tubes is a direct result of the very small temperature gradients available in the ocean, which necessitate a large heat transfer area to transfer sufficient heat. Consequently, optimizing the LMTD becomes a crucial task for achieving an economically viable OTEC plant and it also recommended that the use of chromium alloys should be employed in the manufacturing of OTEC heat exchanger because of the corrosive nature of ammonia refrigerant commonly used.