Question

Can you tell me the relationship between mass flow rate, power, and work? What equation etc.

Answer 1

Let 'M' is mass flow rate in kg/sec and h₁ and h₂ are enthalpy at inlet and outlet of condensor(an example) in KJ/kg, subtract h₂ from h₁ to get delta h and then multiply that delta h (KJ/kg) with mass flow rate 'M' (kg/sec) , after multiplication you will find the units remaining are KJ/sec, which are units of power. As we know power is the rate of work done, the amount of energy transferred per unit time. In the International System of Units, the unit of power is the joule per second (J/s). As is implied by the equation for power, a unit of power is equivalent to a unit of work divided by a unit of time. This is a general way of relating the terms, but in problems related to cycles in thermodynamics, such as turbine in connection with condensor, pump, boiler, we use a simple formula relating these three terms. Power produced(or that is work done)=(mass flow rate)*(net work)

where, Net work = W(turbine out)-W(pump in) , units KJ/Kg

Specific Enthalpy is a measure of the total energy in a unit mass. The SI-unit commonly used is J/kg or kJ/kg.The term relates to the total energy due to both pressure and temperature of a fluid (such as water or steam) at any given time and condition. More specifically enthalpy is the sum of internal energy and work done by applied pressure.

Hope this helps!