The power is proportional to the cube of the pump speed.

You will need to create the pump curves for your pump, or the vendor may have one you can use, or adapt to your fluid with a density coefficient.

http://www.engineersedge.com/fluid_flow/

Can we calculate it for reciprocating pumps also? if yes, how? Is there any thumb rule for this?

Let’s just assume I want a heat exchanger to remove 10,000 BTU/hr. Is there a calculation on how to find it’s physical size. MOC is steel and the fluid in it is water.

Heat exchanger design!