The aim of proposed research study is to develop a customized thermosyphon heat exchanger which works on thermal buoyancy fluid flow conditions and investigate on dynamic conditions during its start-up, thermal load change conditions and shut down conditions. The heat source is maintained by electrical energy source where as heat sink is managed from cold water reservoir. The selected process parameters for this study is thermal load at different heater arrangements, cold water flow conditions, type of fluid, operating conditions. Advanced numerical simulation work will also conduct in this research work using commercial CFD software Ansys Fluent. Optimization of model equation developed for this research work will optimized using MINITAB software by using composite desirability function (CD) technique. A simple and accurate mathematical model for the time-dependent operation of thermosyphon is simulated. The developed model can easily estimate the temperature profiles and time constant of DTTH to examine its stability and normal operation, understand its thermal characteristics and predict its performance.