Now we need to find expressions for the capital cost of the pipes and pumps. In

general, for the entire system the pump capital costs will be assumed to be of the

following form

˙

(2-14)

where *A*1 =

empirical constant ($/pump)

empirical constant ($/W)

number of pumps

∆*P*d =

total pressure drop (supply and return) at design flow rate (N/m2).

The total pressure drop at maximum flow conditions is given by

∆*P*d = *a *εb (4/π)2+*c *A6 md 2+*c *L d(5+*b+c*)

˙

(2-15)

where *A*6 = [(ρ1 *c*)d,s+ (ρ1 *c*)d,r]/2 (m3+*c *sc/kg1+*c*).

So, our pump cost becomes

(2-16)

where *A*5 = *A*2a εb(4/π)2+*c *A7,d md 3+*c *L ($ m5+*b+c*)

˙

For the capital cost of the supply and return piping, including installation, we

assume the following form

(2-17)

where *A*3 = empirical constant ($/m)

The cost of maintenance and repair is assumed to be of the following form

(2-18)

where *A*m&r = annual maintenance and repair rate as a fraction of initial capital cost

(dimensionless)

less).

With each of the component costs defined, our expression for the objective

function, the total cost *C*t, becomes

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