Code Manual for CONTAIN 2.0 - Federation of American Scientists

The capacity-rate ratio CR is defined as
CR= Captin
Cap~m
where Cap~mis the larger of Cap~ and CapC.
(12-26)
The following sections give expressions from Reference Kay64 for the effectiveness E for the four
types of heat exchangers shown in Figure 12-7.
Sinide-Pass Shell and U-Tube Effectiveness. The effectiveness factor E for the heat exchanger with
a single-pass shell and U-tube geometry (Figure 12-7a) is given by
where
E={[1+Cll] + /A (1 + e-r)/(l - e-r]
Equation (12-25) was derived for one shell pass and two tube passes.
(12-27)
Cross-Flow Heat Excharwer Effectiveness. The effectiveness E for across-flow heat exchanger with
hot-side tubes and cold-side shell (Figure 12-7b) depends on whether Cap-= Ca~ or cap- = Capc.
E Capma = Cap~, then E is given by
E = 1 - exp(-r)
where r = CR [1 – exp (–Ntu CR)]. Otherwise, E is given by
E = CR[ 1 - exp(-17)]
where r = CR [1 - exp (–Ntu)]. This model assumes that the shell fluid is mixed.
(12-28)
(12-29)
R O 12 23 6/30/97