at this condition, it will be satisfied at the lower temperature conditions.

For a return temperature of 55C, the saturation pressure is 1.576 104 N/m2

(Reynolds and Perkins 1977). The sum of this and our safety margin is 1.157

105 N/m2. By examining the return pressures in Table 14, we see the constraint of

eq 4-23 is satisfied at all points in the return piping.

Now we look at the two constraints on the pressure in the return line at the heating

plant, eq 4-24 and 4-25. We see that, for the parameter values chosen, eq 4-24 will

dominate. Equation 4-24 requires that the pressure in the return line at the heating

plant be greater than 2.0 105 N/m2. The pressure in the return line at node number

this constraint is satisfied as well. Thus, our design has satisfied all the constraints

specified.

73

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