Radiator

if we are talking about an internal combustion engine, the the expandion vale is in the radiator cap. a engine can not excede a remperature above 210 degrees without major damage. you need a radiator, fan and thermostat to draw off essessive heat. you have posted this question several times. either take our advise or ruin enough engines to learn the hard way. either way, quit bothering us with you stupidity.

i have posted this question first time and your answer was not satisfactory

Your question lacks clarity. There are many types of radiators.

Please review this Wikipedia article about radiators and see if it helps.

If not, please tell us more and we might be able to answer more specific questions.

radiator top tank and expansion tanks have the same function. Radiators typically have top tanks above their core structure and expansion tanks are typically found in heat exchanger systems ( e.g shell and tube or plate heat exchangers). The function of these two tanks is to provide room for the hot coolant to expand ( fluid expands when heated)