Work input to a pump in a rankine cycle problem

[jemb]

If a question asks for the "quantity of work input to the pump" is it acceptable to present the answer as positive.

I think so because the direction of energy transfer has been defined in the question itself hence there is no need for a sign on the answer. All that's asked for is the quantity. However my thermodynamics lecturer disagrees and is refusing to award the marks for the answer in a recent coursework submission.

I understand why work input in thermodynamics is negative, but surely an unsigned figure is permissible if the direction of energy transfer is defined for you.

Am i wrong?

 

[rock.freak667]

Usually the sign convection for work done is that work done by something is positive while work into a system is negative.

Since you are inputting work to a system, then the work done by the pump is negative.

This is why the turbine does positive work.

(Apply the steady state steady flow equation to the pump and you will see)