Kah Aik Tan I think for preliminary Analysis, you can use Q=mcpT with the assumption of Qhot=Qcold as the ideal case (negligible heat losses) but if you want to accommodate the effect of heat exchanger configuration you have to use Q=UAT.

I agree. Plus, of course the flow rate of the water also depend on the output temperature you will have for the water (if your heat exchanger works in counterflow, it will be higher than 60C).

If you need additional info on heat exchangers you may find something relevant here: https://www.pdhonline.com/courses/m371/m371content.pdf

Hi Kah Aik Tan

To answer whether you can assume 85 KW as Q, you have to be careful that rate of generated heat depends on the rate of reacting methane. So if the volumetric flow of methane is constant throughout your studies, then 85 KW can be true (If the number 85 is derived correctly)

As a preliminary guess, thermodynamical equation Q=m*cp*deltaT may be used but it's almost useless and not recommended.

To have a correct estimation of the volumetric flow rate, of cooling water, you have to derive U and A from Q=U*A*deltaT.

Because of high temperature and existence of reaction in the system, no normal shell&tube is applicable. My guess for your use is a furnace.

For calculation of U, heat transfer is done via convection and radiation mechanisms and there are figures and tables in books (you may find most useful information in furnace design books) to help you in this matter.

For calculation of A, the outer area of cooling water tubes in the designed furnace must be calculated.

For calculation of deltaT, you have to be careful that the logarithmic temperature difference is used. You can search the formula on the Internet.