Shell-side Heat Transfer Coefficient Research Articles

Derivation of Charts for the Approximate Determination of the Area Requirements of Heat Exchangers Using Plain and Low-Finned Tube Bundles (Part A)

Heat exchangers can be made more compact by either enhancing the heat transfer coefficient or by increasing the amount of area per unit volume. The use of low-finned tubes is an effective means of achieving the latter. The extent to which the equipment size can be reduced using such means is problem-dependent. Decisions of whether or not to employ process intensification have to be made at the conceptual stage of design. There is, therefore, a need for sizing procedures that avoid the recourse to full detailed design. Such a procedure is reported here. The key to the procedure is a relationship between the shell-side pressure drop, shell-side heat transfer coefficient and overall exchanger surface area. The procedure has been applied to a number of ‘typical’ fluids. The results are presented in a series of charts relating exchanger size and duty. It is shown how individual duties can be ‘normalized’ in the form of a ‘duty factor’ that relates shell-side pressure drop, mass flow rate, stream temperature change and exchanger temperature driving force. So, the charts are independent of duty.

97/02066 Performance of a wind-turbine-driven compressor for lifting water

Flow resistance and heat transfer of several shell-and-tube heat exchangers with discontinuous helical baffles are experimentally studied and compared at the five helix angles of 8°, 12°, 20°, 30° and 40°. The second-law based thermodynamic analysis is employed to analyze the effects of baffle helix angle on the irreversible loss of heat exchangers. The results indicate that the shell-side pressure drop and heat transfer coefficient of the heat exchanger with smaller helix angle are higher than those with larger helix angle at a given shell-side volume flow rate. However, in the condition of the same shell-side Reynolds number, the flow resistance with larger helix angle is lower and the heat transfer performance is better. The heat exchanger with helical baffles at 40° helix angle presents the best comprehensive performance among the five testing heat exchangers. In the second-law thermodynamic comparisons, the irreversibility of heat exchanger is estimated by the theories of entropy generation and entransy dissipation. Experimental analysis shows that in the same heat transfer area and under the same working conditions, the shell-and-tube heat exchanger with smaller helix angle baffles produces less irreversibility in the heat exchange process. In addition, the heat exchangers with helical baffles are more effective under certain conditions of low shell-side Reynolds number.

Transient behaviour of multipass shell-and-tube heat exchangers

A method for predicting the transient responses to arbitrary inlet temperature changes of multipass shell-and-tube heat exchangers with arbitrary number of tubeside passes is developed. The tubeside as well as shellside surface areas and heat transfer coefficients are allowed to be different from pass to pass. The thermal capacities of both fluids and the wall are included. Both possible flow arrangements are considered. The inlet temperature changes may take place on either side or simultaneously on both sides. Generally, the optimum value of M of the summed series terms for the numerical inverse Laplace transform falls in the range 8⩽ M ⩽ 20.

Shellside heat transfer coefficients in cylindrical heat exchangers. Variation along the exchanger length, I — The no-leakage case: Experimental

Heat transfer coefficients, determined by an electrochemical analogue method, are reported for the complete length of a shell-and-tube heat exchanger model. The model had segmented electrodes placed at 20 locations in its 80 tube bundle.

Determination of Shell-Side Heat Transfer Coefficients by the Naphthalene Sublimation Technique

Abstract Experiments are described in which shell-side heat transfer coefficients for a shell-and-tube heat exchanger were determined from mass transfer measurements. The mass transfer experiments were carried out using the naphthalene sublimation technique. In utilizing the technique, the external surface of the tubes is coated with a film of naphthalene, which sublimes when exposed to an air flow. Mass transfer coefficients were measured for fully developed flow conditions at each of the tubes in the cross section. These coefficients were transformed to heat transfer coefficients by employing the analogy between heat and mass transfer. Detailed pressure drop measurements were made internal to the heat exchanger, and the axial pressure distribution indicated that the fluid flow was fully developed downstream of the first compartment. The cross-sectionally averaged mass (heat) transfer coefficients and the pressure drop were compared with the predictions from two well-established methods for the thermal-h...

Mean Temperature Difference for Shell-and Tube Heat Exchangers with Condensing on the Shell Side

Shetl-and-tube heat exchangers with condensing on the shell side usually have a nonlinear heat release curve and a variable shell-side heat transfer coefficient. Using an effective average coolant temperature, it is possible to separate the calculation of the mean temperature difference from the heat transfer coefficient. Thus, it is possible to calculate the weighted mean temperature difference before the heat transfer coefficients are calculated. As a result, the complexity of the calculations is greatly reduced from present incremental procedures. When compared to a detailed incremental calculation of the mean temperature difference, tht maximum error is about 2%. A manual incremental method is also presented, which requires only moderately more work than industrial methods that use average heat transfer coefficients.

Shell-side heat transfer coefficients in cylindrical heat exchangers the influence of geometrical factors. II — the leakage case

The mass-transfer analogue method, used previously to measure heat transfer coefficients in a single internal compartment of a small cylindrical shell-and-tube heat exchanger model, has been used to study the case where clearances exist between shell and baffle, and between tubes and baffle, for one baffle-spacing, with various flow configurations, and varying baffle-cut. Baffles of two thicknesses with the same ‘Z’ factor, gave different results, contrary to the accepted view. These preliminary results show the need for further work.

Shell-side heat transfer coefficients in cylindrical heat exchangers. The influence of geometrical factors. I - the non-leakage case

A mass transfer analogue technique has been used to obtain heat transfer coefficients for an individual baffle compartment in a small cylindrical heat exchanger model, for two baffle spacings and three baffle cuts under non-leakage conditions. Various forms of correlation were applied to the data and found to be inadequate. Development of any improved correlation will require further experimental work.

Predicting flow induced vibration in u-bend regions of heat exchangers: an engineering solution

From the standpoint of flow induced vibrations, U-bends of tubular heat exchangers constitute structurally one of the most vulnerable regions. The U-bends possess relatively low out-of-plane frequency enabling them to extract energy from the shell stream at low flow velocities. All published correlations in the literature imply the existence of a direct relationship between the flow velocities and the incidence of large ampitude tube vibrations. Hence it is important to determine the velocity profile in the U-bend region accurately. A method to obtain an engineering solution is proposed herein which may be utilized in conjunction with the available correlations to reliably predict the possibility of vibration. Determination of the flow profile may be further utilized to improve the estimates of shellside heat transfer coefficients.

Shell-Side Heat Transfer Coefficients in Helical Coil Heat Exchangers

Shell-Side Heat Transfer Coefficients in Helical Coil Heat Exchangers

Flow Patterns for Predicting Shell-Side Heat Transfer Coefficients for Baffled Shell-and- Tube Exchangers

Flow Patterns for Predicting Shell-Side Heat Transfer Coefficients for Baffled Shell-and- Tube Exchangers