The impact of manifold design on single-phase heat exchanger effectiveness is studied using the NTU-Effectiveness method. Manifolds are devices that redistribute the internal flow stream of a heat exchanger from one to several passages. Two manifold types are identified: collector box and direct split designs. The particular application considered is that of a gas fired forced air heating system. A general enhancement analysis is performed which covers four different combinations of performance and objective criteria. Three cases involve increasing the heat exchanger effectiveness while constraining either the internal flow head loss, the internal mass flow rate, or their product. The other case involves reducing the required heat exchanger flow length while constraining the heat transfer rate. Familiar convection correlations are then incorporated into the enhancement analysis to predict general trends and behavior when the main tube is split into several smaller tubes. Analytical estimates of improved effectiveness are presented for three operating conditions of an actual heat exchanger which possesses a manifold. Experimental data acquired from the gas-to-gas heat exchanger are compared to numerical predictions of its performance without a manifold (baseline design). The analytical equations developed closely predict the improvement in heat exchanger effectiveness.

1.
Burmeister, L., 1993, Convective Heat Transfer, second ed, John Wiley & Sons, New York, NY, pp. 111–115.
2.
Churchill
S. W.
, and
Berstein
M.
,
1977
, “
A Correlating Equation for Forced Convection From Gases and Liquids to a Circular Cylinder in Cross Flow
,”
ASME JOURNAL OF HEAT TRANSFER
, Vol.
99
, pp.
300
306
.
3.
Gnielinski
V.
,
1976
, “
New Equations for Heat and Mass Transfer in Turbulent Pipe and Channel Flow
,”
International Chemical Engineering
, Vol.
16
, pp.
359
368
.
4.
Joye
D. D.
, and
Cote
A. S.
,
1995
, “
Heat Transfer Enhancement in Annular Channels With Helical and Longitudinal Fins
,”
Heat Transfer Engineering
, Vol.
16
, No.
2
, pp.
29
34
.
5.
Kays and Crawford, 1993, Convective Heat and Mass Transfer, second ed., McGraw-Hill, Hightstown, NJ, pp. 316.
6.
Notter
R. H.
, and
Sleicher
C. H.
,
1972
, “
A Solution to the Turbulent Graetz Problem-III
,”
Chemical Engineering Science
, Vol.
27
, pp.
2073
2093
.
7.
Ravigururajan, T. S., and Rabas, T. J., 1993, “An Overview of Single-Phase In-Tube Enhancements: Part 1—Data-Base Development,” ASME 93-WA/HT-38, pp. 1–8.
8.
Shah, R. K., and London, A. L., 1978, “Laminar Flow in Forced Convection Ducts,” Advances in Heat Transfer, Academic Press, New York, NY.
9.
Webb
R.
,
1982
, “
Performance Evaluation Criteria for Use of Enhanced Heat Transfer Surfaces in Heat Exchanger Design
,”
International Journal of Heat and Mass Transfer
, Vol.
24
, pp.
715
726
.
10.
Webb, R., 1994, Principles of Enhanced Heat Transfer, John Wiley & Sons, New York, NY.
This content is only available via PDF.
You do not currently have access to this content.