Modeling of plate heat exchangers with generalized configurations

Krishi Sanskriti Publications , 2017

In this work, a model of compact heat exchanger, Gasketed Plate type heat exchanger set up has been investigated and analysed. The plate type heat exchanger made of SS 316 having chevron angle 30 o has been designed and fabricated to for experimental analysis. The hydraulic parameters have been changed to observe its effect on thermal performance of Plate Heat Exchanger as the Reynolds Number is varied from 600 to 6500. The mass flow rate, dimensions of plate, pressure difference between the plates and temperature at the inlet and outlet port of Gasketed Plate Type Heat Exchanger are measured. The Kumar Correlation for Nusselt Number which is the function of Prandtl Number and Reynolds Number has been used to calculate the convective heat transfer coefficient and the Overall heat transfer coefficient. The mathematical simulation of physical dimensions of plate type heat exchanger such as plate length, width, spacing and thickness has been done using simulation and its effect on overall heat transfer coefficient and pressure drop has been analyzed. The outcomes of these volumetric flow variations on test setup and mathematical simulation has been verified with theoretical analysis.

Chemical Engineering Science, 2004

Thermal models of plate heat exchangers rely on correlations for the evaluation of the convective heat transfer coefficients inside the channels. It is usual to configure the exchanger with one countercurrent single-pass arrangement for acquiring heat transfer experimental data. This type of configuration approaches the ideal case of pure countercurrent flow conditions, and therefore a simplified mathematical model can be used for parameter estimation. However, it is known that the results of parameter estimation depend on the selected exchanger configuration because the effects of flow maldistribution inside its channels are incorporated into the heat transfer coefficients. This work presents a parameter estimation procedure for plate heat exchangers that handles experimental data from multiple configurations. The procedure is tested with an Armfield FT-43 heat exchanger with flat plates and the parameter estimation results are compared to those obtained from the usual method of single-pass arrangements. It can be observed that the heat transfer correlations obtained for plate heat exchangers are intimately associated with the configuration(s) experimentally tested and the corresponding flow distribution pattern(s).

Compact heat exchangers are most widely used for heat transfer applications in industries. Plate heat exchanger is one such compact heat exchanger, provides more area for heat transfer between two fluids in comparison with shell and tube heat exchanger. The present work deals with experimental heat transfer data performed on plate type heat exchanger which is used in hydraulic cooling system in an industry. The heat exchanger used for carrying out this work consists of thin metal welded plates of stainless steel with 0.5mm thickness; distance between two plates is 5mm, chevron angle 60° and counter flow arrangement. The total heat transfer area is 161.62 m2. This consists of total 249 numbers of plates and it is designed to withstand with 65°C temperature with a flow rate of 64751 kg/h and cold fluid enters with a flow rate of 82366 kg/h at 35°C and leaves at 44.29°C, pressure drop is neglected. The inlet and outlet temperatures of cold and hot fluids are been observed and with that conditions performance evaluation is done. Based on the experimental data, a correlation will estimate for Nusselt number as a function of Reynolds number, Prandtl number and chevron angle and the outputs obtained are convective heat transfer coefficient, overall heat transfer coefficient, and exchanger effectiveness. From the obtained results, graphs are drawn to assess the performance of the Gasketed Plate heat exchanger.

Chemical Engineering and Processing, 2002

Plate heat exchangers are making their presence felt in the power and process industry in the recent past. Hence, it has become necessary to model their temperature response accurately. The traditional way of modelling a plate heat exchanger with equal flow in all the channels is unrealistic, and previous studies indicate that considerable differences remain in the flow rates in different channels. The present work brings out the effect of flow maldistribution from channel to channel comprehensively. This poses a serious question about the usual method of analysis of the experimental heat-transfer data of the plate heat exchanger. Unlike previous studies, the present study indicates the importance of considering the heat-transfer coefficient inside the channels as a function of flow rate through that particular channel. This eliminates the contradictory proposition of unequal flow rates but an equal heat-transfer coefficient. A wide range of parametric study have been presented, which brings out effects such as those of the heat-capacity rate ratio, flow configuration, number of channels and correlation of heat transfer. The analysis presented here suggests a better method of heat-transfer data analysis for plate heat exchangers.

International Journal of Heat and Mass Transfer, 2004

A screening method is presented for selecting optimal configurations for plate heat exchangers. The optimization problem is formulated as the minimization of the heat transfer area, subject to constraints on the number of channels, pressure drops, flow velocities and thermal effectiveness, as well as the exchanger thermal and hydraulic models. The configuration is defined by six parameters, which are as follows: number of channels, numbers of passes on each side, fluid locations, feed relative location and type of channel flow. The proposed method relies on a structured search procedure where the constraints are successively applied to eliminate infeasible and sub-optimal solutions. The method can be also used for enumerating the feasible region of the problem; thus any objective function can be used. Examples show that the screening method is able to successfully determine the set of optimal configurations with a very reduced number of exchanger evaluations. Approximately 5% of the pressure drop and velocity calculations and 1% of the thermal simulations are required when compared to an exhaustive enumeration procedure. An optimization example is presented with a detailed sensitivity analysis that illustrates the application and performance of the screening method.

Heat Transfer Engineering, 2021

Thermal design and analysis of heat exchangers are predominantly conducted considering constant heat transfer coefficients. However, these vary along the length and affect the calculations of heat transfer rates and area allocations. The current paper investigates the variations in the heat transfer coefficients in plate heat exchangers (PHX), using different numerical approaches. The heat transfer coefficient is calculated at the inlet, outlet, and systematically selected intermediate points for each method. The analysis is conducted for two different systems, i.e., a laboratory-scale and an industrial scale PHX at different chevron angles. It is concluded that the effect of the variable heat transfer coefficient is more significant for the large-scale heat exchanger due to high flow rates, geometrical specifications, Reynolds number, and thermophysical properties. The deviation of the local heat transfer coefficient along the heat exchanger length is approximately 9-14 % and 3-6% for industrial and laboratory scale PHX, while an area deviation of around 15% is observed.

The primary focus of this paper is to evaluate the performance of a Plate type heat exchanger. The evaluation is carried out for namely two heat transfer parameters, heat transfer coefficient and heat exchanger effectiveness for varying Reynolds number of hot and cold fluids. From the experimental values of inlet and outlet temperatures measured, the above two parameters were calculated. The analytical approach for calculation is illustrated for one sample reading. The heat transfer coefficient and heat exchanger effectiveness was seen to increase with increasing Reynolds number of both the fluids. A PHE belongs to the family of compact plate heat exchangers. Therefore, the secondary objective was to compare the PHE with conventional heat exchanger i.e. Double pipe. The comparison was done on the basis of area required for a given temperature drop and heat transfer capacity. The numerical values of areas obtained confirmed that a PHE requires the least space for operation.

2012

This paper presents simulation investigation of a plate heat exchanger. Basically, it includes the development of a mathematical model to describe its operation and analysis. The model, after testing against the existing experimental data, has been solved to obtain the effect of various parameters like mass flow rate, number of flow channels, plate configuration and flow patterns. Model of a plate heat exchanger has been described by a set of continuity, momentum and energy equations with a number of simplifying assumptions. Heat transfer rate equation has also been included in the energy balance equation to take care of phenomena occurring therein. Mathematical model has been solved by the use of finite difference technique with interval of Δt =0.005s and Δz = 0.005m to obtain the transient and steady state behavior.

Thermal Science, 2022

Due to compact size, high power density, low cost and short construction time, the small modular reactors are considered as one of the candidate reactors, in which the power generation system is important with a compact heat exchanger for modular construction. Therefore, the effect of plate structure and nature of the working fluid on the thermal performance of plate heat exchanger are analyzed for the design of compact and efficient heat exchanger. The heat transfer rate, temperature counters, velocity vectors, and pressure drop have been optimized and investigated using FLUENT. The Nusselt number has been calculated for the corrugated and flat plate heat exchanger to validate the convective heat transfer. The numerical results are agreed well with correlation within deviation of ~5-7%. The performance of heat exchanger can be improved by controlling the mass-flow rate, and temperature of working fluid. The corrugation plate heat ex-changer increases the heat transfer rate 20% and ...

In this work we present a theoretical-experimental research on the thermal phenomena that the endplates present on the performance of the plate heat exchangers in a single step and with a U type configuration. The endplate effect is reflected in a reduction of the temperature difference for heat transfer. The model discusses a theoretical focus that includes the elongation factor, which is a parameter that relates the actual area to the projected area of a plate. This model was performed to 2, 3, 4, 5, and 6 channel flow; therefore the experimentation was carried out to validate the theoretical model, it was carried out for 4, 5, 6, 7, 8 and 9 flow channels. Such results show that the theoretical model deviates in a 5% of the experimental values. The results obtained for theorical temperature correction factor presents a maximum deviation of ± 0.0245 with respect to the experimental values.