Considering an engine generating thermal heat at 140 kw and when the generation starts the thermal equilibrium of the engine will be distrubed , a radiator is installed to cool the engine this radiator cool the engine through flow of water and water is cooled inside a heat exchanger with air . I set a transient equation to my system but I am still unable to solve it please check my equation if it is correct and if there is anything missing . Qgen+mdot.cp water.(Tentring water - T exiting water)=[tex]\rho[/tex]C .V . dTengine/dt P.S:ignoring radiation trasfer. Qgen = 140 kw . mdot water=0.37m3/s. cpwater=4.1855 J/(g·K) C cast iron=0.46 Rho=7870KG/m3. v=>volume=0.01m3. Initial conditions: at t=0sec Tengine = 45 Deg Twater entring = 30 deg c How can I design a radiator for such system , after solving the equation I still have 2 unknowns Thot air and T2 engine . From the above how can I identify the area of my heat exchanger ?