Please use this identifier to cite or link to this item: https://scholarbank.nus.edu.sg/handle/10635/153429
Title: THERMAL PERFORMANCE STUDY OF A SPIRAL COIL HEAT EXCHANGER
Authors: SOMASUNDARAM RAJASEKAR
Issue Date: 1994
Citation: SOMASUNDARAM RAJASEKAR (1994). THERMAL PERFORMANCE STUDY OF A SPIRAL COIL HEAT EXCHANGER. ScholarBank@NUS Repository.
Abstract: A spiral coil heat exchanger (SCHE) consists of a number of horizontal layers of concentric, spirally wound finned tubes connected to vertical manifolds at the inner and outermost turns of each coil. In operation, the gas flow can be directed to flow outwards radially from the inside or central core to the outside, or in the opposite direction. The liquid flow in the coiled tubes is countercurrent to the gas flow, whichever gas flow path is selected. To predict the performance of SCHE, two theoretical models, unmixed and mixed-air-flow models, are developed based on unmixed-air-flow and mixed-air-flow considerations. The unmixed-air-flow model is an exact model and is developed on the basis of an assumption that the air flow is not mixed as it flows over finned spiral coils. The mixed-air-flow model is a simplified model developed by assuming that after each tum, the outer fluid flow is mixed and at some mean temperature. The empirical formulae to predict the inside and outside heat transfer coefficients and the pressure drop characteristics of the SCHE are identified. In order to validate these two theoretical models and to verify the empirical correlations identified to predict the internal and external heat transfer coefficients and the pressure drop characteristics, two laboratory models of spiral coil heat exchanger, SCHE I and ll, are fabricated. Two systems, an open and a closed system, are constructed to study the heat transfer and pressure drop characteristics of SCHE I and II over a wide range of operating conditions. Experimental data of both SCHE I and II are compared with the values predicted by the theoretical models. The pressure drop measurements made inside and outside the spiral coils of SCHE I and II and in a bare tube spiral coil are compared with those values predictcd by the empirical formulae. Experimental data obtained from SCHE I and II confirmed very well with the predicted results of the unmixed and mixed-air-flow models of the SCHE. The applicability of the empirical formulae for the internal and external heat transfer coefficients was also confirmed.
URI: https://scholarbank.nus.edu.sg/handle/10635/153429
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