Model Of Plate Heat Exchanger Research Articles

Optimal design of organic Rankine cycles for exhaust heat recovery from light-duty vehicles in view of various exhaust gas conditions and negative aspects of mobile vehicles

The organic Rankine cycle (ORC) is a promising method of recovering the exhaust heat of the internal combustion engine (ICE). However, the off-design exhaust conditions and the negative effects (such as increased backpressure and added weight) of the ORC installation onto vehicles greatly deterioratetheperformanceof ORC applied on mobile vehicles. In this paper, the ORC thermodynamic model with an integrated plate heat exchanger model is developed to evaluate the effects of sizing the heat exchanger and designing the ORC operating conditions on the thermodynamic performance of the ORC system. Considering various major exhaust conditions and the negative impacts of ORC system installation on vehicles, an optimal ORC system design strategy is proposed to maximize the net output power. The optimum geometric parameters of heat exchangers and ORC operating conditions are simultaneously designed through a mixed integer nonlinear programming problem. The proposed design strategy is compared with the design method without considering negative effects and the design method only based on one major engine operating point. The comparison results indicate that the proposed design strategy increases the weighted net output power and the proposed design strategy can ensure that the ORC works normally in various exhaust conditions. Among all the operating parameters, the size of the heat exchanger (two geometric parameters) is the major factor affecting the performance of ORC. These findings highlight the importance of considering various exhaust conditions and the negative impacts of vehicle-mounted ORC during the design procedure.

Multi-Scale CFD Modeling of Plate Heat Exchangers Including Offset-Strip Fins and Dimple-Type Turbulators for Automotive Applications

Plate heat exchangers including offset-strip fins or dimple-type turbulators have a wide application in the automotive field as oil coolers for internal combustion engines and transmissions. Their optimization is a complex task since it requires targeting different objectives: High compactness, low pressure drop and high heat-transfer efficiency. In this context, the availability of accurate Computational Fluid Dynamics (CFD) simulation models plays an important role during the design phase. In this work, the development of a computational framework for the CFD simulation of compact oil-to-liquid heat exchangers, including offset-strip fins and dimples, is presented. The paper addresses the modeling problem at different scales, ranging from the characteristic size of the turbulator geometry (typically µm–mm) to the full scale of the overall device (typically cm–dm). The simulation framework is based on multi-scale concept, which applies: (a) Detailed simulations for the characterization of the micro-scale properties of the turbulator, (b) an upscaling approach to derive suitable macro-scale models for the turbulators and (c) full-scale simulations of the entire cooler, including the porous models derived for the smaller scales. The model is validated comparing with experimental data under different operating conditions. Then, it is adopted to investigate the details of the fluid dynamics and heat-transfer process, providing guidelines for the optimization of the device.

Experimental investigation of a plate heat exchanger model for lithium bromide absorption chillers: first results

In this paper the results of thermal-hydraulic tests of a sample of a perspective plate heat exchanger under the conditions of LBAHT is described. Working opportunity of the sample working under conditions of LBAHT has been confirmed by this research.

Modeling of plate heat exchanger based on sensitivity analysis and model updating

In this paper, an efficient modeling method for plate heat exchanger (PHE) is developed. Firstly, the mechanistic model is established according to heat transfer equation and heat balance equation. Due to the existence of multiple unknown parameters in the mechanistic model, sensitivity analysis is employed to study the influence of these parameters on the model output. Then, the parameters which have a significant influence on the model output are estimated using real data, and the values of parameters with low influence on the output are acquired from previous works. With PHE running, the performance of PHE deteriorates due to the fouling deposits on plate surface, the corrosion and erosion damages to plates and other unknown factors. To track the changes of outlet cooling water temperature caused by above factors, Gaussian mixture model (GMM) is used to assess the performance of mechanistic model. According to the assessment results, model output offset updating or model parameter updating is activated. Finally, the feasibility and efficiency of the proposed modeling method are demonstrated by applications to three PHEs in a steel plant. The presented modeling method lays an important foundation for energy-saving optimization of circulating cooling water system.

Experimental Study of a Bubble Mode Absorption with an Inner Vapor Distributor in a Plate Heat Exchanger-Type Absorber with NH3-LiNO3

Absorption systems are a sustainable solution as solar driven air conditioning devices in places with warm climatic conditions, however, the reliability of these systems must be improved. The absorbing component has a significant effect on the cycle performance, as this process is complex and needs efficient heat exchangers. This paper presents an experimental study of a bubble mode absorption in a plate heat exchanger (PHE)-type absorber with NH3-LiNO3 using a vapor distributor in order to increase the mass transfer at solar cooling operating conditions. The vapor distributor had a diameter of 0.005 m with five perforations distributed uniformly along the tube. Experiments were carried out using a corrugated plate heat exchanger model NB51, with three channels, where the ammonia vapor was injected in a bubble mode into the solution in the central channel. The range of solution concentrations and mass flow rates of the dilute solution were from 35 to 50% weight and 11.69 to 35.46 × 10−3 kg·s−1, respectively. The mass flow rate of ammonia vapor was from 0.79 to 4.92 × 10−3 kg·s−1 and the mass flow rate of cooling water was fixed at 0.31 kg·s−1. The results achieved for the absorbed flux was 0.015 to 0.024 kg m−2·s−1 and the values obtained for the mass transfer coefficient were in the order of 0.036 to 0.059 m·s−1. The solution heat transfer coefficient values were obtained from 0.9 to 1.8 kW·m−2·K−1 under transition conditions and from 0.96 to 3.16 kW·m−2·K−1 at turbulent conditions. Nusselt number correlations were obtained based on experimental data during the absorption process with the NH3-LiNO3 working pair.

Mathematical Modelling of the Thermal and Hydraulic Behaviour of Plate Heat Exchanger in the Fouling Conditions

The mathematical model of Plate Heat Exchanger (PHE) subjected to fouling is proposed. It is represented by the system of ordinary differential equations. The model is accounting for the distribution of process parameters along the PHE channel that allows predicting fouling development in time at different locations along the channel length. The development of the fouling deposit is accounted with the fouling model presented by the equation in dimensionless form. The relative influence of different terms is characterized by empirical coefficients which can be identified with the data of monitoring the PHE thermal and hydraulic performance. The model allows also the prediction of pressure drop variation in PHE with the development of fouling deposition layer and respective reduction in channels cross-section area. The application of the model and its accuracy is demonstrated with two case studies considering the monitoring of PHEs thermal and hydraulic performance in the industry at sugar factory and in District Heating system.

Mathematical Model of Plate Heat Exchanger for Utilisation of Waste Heat from Condensable Gaseous Streams

The mathematical model of vapour condensation from the mixture with noncondensing gas in Plate Heat Exchanger (PHE) channels is presented. The model accounts for the change of process parameters along the heat transfer surface and local features of heat and mass transfer processes in PHEs channels with plates of different corrugations geometry. It consists of the system of ordinary differential equations with considerably nonlinear right parts. The software for its solution by finite difference method is developed. The validity of the model is confirmed by comparison with the experiment for steam-air mixture condensation in a PHE channel sample.

Accounting for local features of fouling formation on PHE heat transfer surface

The fouling phenomena can create significant operational problems in the industry by deteriorating heat recuperation, especially in heat exchangers with enhanced heat transfer. For a correct prediction of fouling development, the reliable fouling models must be used. The analysis of existing fouling models is presented. The chemical reaction and transport model developed earlier for a description of fouling on intensified heat transfer surfaces is used for modeling of plate heat exchanger (PHE) subjected to fouling. The mathematical model consists of a system of differential and algebraic equations. The integration of it is performed by finite difference method with developed software for personal computer. For countercurrent streams arrangement in PHE the solution of two-point boundary problem is realized on every time step. It enables to estimate local parameters of heat transfer process with fouling formation and its development in time with the growth of deposited fouling layer. Two examples of model application in cases of PHEs working at sugar factory and in district heating network are presented. The comparison with experimental data confirmed the model validity and the possibility of its application to determine the performance of PHE subjected to fouling. Open image in new window

Application of LabVIEW and Genetic Algorithm for controlling of Plate Heat Exchanger

The mathematical modeling of plate heat exchanger (PHE) was studied by effect several step change in entrance hot fluid stream and measuring the temperature of exit cold fluid. Based on the energy balance, a mathematical model for this heat exchanger (PHE) transmit factor (U) is linked with the warm fluid stream (mh). To confirm this model, the control on temperature was applied experimentally and theoretically to the plate heat exchanger using P, PI and PID controllers with some different tuning methods of control parameters; genetic alg - To assess the achievement of control, the time domain specifications such as rise time, overshoot (OS), settling time, measures of control system efficiency (integrates the square of the error over time (ISE) and integrates the absolutes error over time (IAE)) are used. The PID controller gave better control of temperature than other controllers, While Ziegler – Nichols method gave better control than Cohen-Coon. Genetic Algorithm (GA) technique is the best method in simulation compared with Cohen-Coon and Ziegler – Nichols methods because of the semi-perfect regulation of adjusted parameter values that give lower oscillatory pattern, minimal sum error, but it gives the slower response to reach the steady state.

Design of a combination package of heat exchanger and heater for organic rankine cycle power plant

This paper presents the capacity of a heat exchanger with a plate heat exchanger model as evaporator and condenser to liquefy and evaporate R-134a refrigerant as the working fluid in a power plant system by operating an Organic Rankine Cycle (ORC) system using a scroll type expander. The evaporating and liquefying refrigerant as the working fluid uses hot water at a temperature between 40 °C - 80 °C and an evaporator inlet temperature at between 24.1 °C – 28.5 °C. The model design of the hot water production system is a combination of heat exchanger and heater with a shell and tube construction, where the heater is immersed in the heat exchanger. Experimental results show that the average revolutions of the turbine expander scroll is about 348.2 rpm and thermal efficiency between the evaporator and condenser as the heat exchanger ranges from 2 % to 8.5 %.

A Grey-Box Dynamic Model of Plate Heat Exchangers Used in an Urban Heating System

This paper deals with the establishment of a grey-box model of plate heat exchangers. First, a second-order state space model of plate heat exchangers is developed. Then, the model is solved by the white-box method and grey-box method, respectively. In the white-box method, the linearization of the state space model is carried out by implicit difference scheme and the overall heat transfer coefficient was calculated with empirical correlation of the Nusselt number. In the grey-box method, a newly developed parameter identification method was established. The simulation results of two outlet temperatures by the grey-box and white-box method, respectively, are compared with the test data. It is shown that the grey-box method is more suitable and accurate for the simulations of outlet temperatures than the white-box method. Thus, it can provide practitioners and heating engineers with tools to design controllers for district heating systems.

Operation stability analysis of district heating substation from the control perspective

Since the heating substation plays a key role in transferring the thermal energy from the primary network to the secondary network and controlling the heat output of district heating system to meet the thermal load, high operation performance of heating substation is essential for energy conservation, cost saving and emission reduction. The dynamic operation stability of heating substation is a very important dynamic characteristic of heating substation and largely affects the operation efficiency of district heating system. The operation instability of heating substation mainly manifest as flow rate and pressure oscillations, which will deteriorate the network hydraulic condition, break the network thermal balance, reduce the consumer comfort and increase the energy cost of the pumping system. Since heating substations will easily operate unstably under some conditions, this paper presents a theoretical method to analyze the stability and retune the feedback controller for operation stability of heating substation. Mathematical model of the plate heat exchanger was established and the feedback control theory was adopted to study the operation stability of heating substation. Based on the mathematical model and feedback control theory, a stability criterion was proposed for analyzing the operation stability of district heating substation effectively. The dynamic model of plate heat exchanger was validated with measured data. Simulation results show that controller tuned at certain operating condition can’t ensure operation stability of heating substation, when operating condition varies in large range. The stability analysis method proposed in this paper can be applied to analyzing the operation stability and tuning the controller of heating substation to enhance the operation stability.

Application of a novel multi-objective optimisation method integrated with the artificial neural networks for optimum design of a plate heat exchanger

In the current study, a plate heat exchanger model is optimised using a multi-objective evolutionary algorithm/decomposition. Considering the importance of the thermal efficiency and the cost of manufacturing the heat exchangers, these two parameters are used as objective functions during the optimisation process. For the purpose of analysis, the ε-NTU method was applied to analyse the probability values for the pressure drop and efficiency of the heat exchanger. The experimental data for the analysis were extracted from a gas furnace in a ceramics factory located in the Kerman province. The results of the analysis reported 19.962% enhancement in the efficiency rate as well as 9.533% reduction in cost through the proposed model, which indicated a significant improvement. In another section of this study, by performing a Pareto front analysis, the distribution of the optimum points for the design variables was outlined. As well as that, the correlation between the objective functions and the design variables by employing the artificial neural networks was discussed. The obtained results were then compared with the two reference cases to achieve a better insight towards the new developed model scheme. At the last stage of study, an error analysis concluded that in most cases, the performance and cost error rates are close to zero with the maximum values being in the range of 0.6–1 and 0–0.13, respectively.

Modelling of Plate Heat Exchangers and Their Associated CO 2 Trancritical Power Generation System

Globally, there is no shortage of low-grade waste and renewable heat sources that can be converted into electricity and useful heat using applicable thermodynamic power cycles and appropriate working fluids. As a natural working fluid, CO2 is a promising candidate for application in low-grade power generation systems but require optimised design and evaluation. Since CO2 working fluid has a low critical temperature (31.1̊C) and high critical pressure (73.8 bar), a CO2 low-grade power generation system will most likely undergo supercritical Rankine (T-CO2) cycles. A T-CO2 system normally consists of a CO2 supercritical gas heater, expander, recuperator, condenser and liquid pump with the CO2 gas heater being a crucial component in determining system thermal and exergy efficiencies. In this paper, the models of a thermal oil-CO2 plate gas heater has been developed and validated with measurements of a 5 kWe T-CO2 system test rig. The model is then integrated with other system component models to establish the system model. The system model can be used to evaluate and compare system performances at different operating conditions, including variable CO2 gas heater pressures and heat sink parameters, thereby optimising system operations.

Simplified dynamical input–output modeling of plate heat exchangers – case study

In this paper, the simplified dynamical modeling of PHEs (plate heat exchangers) is suggested and validated based on realistic measurement data. The concept combines general distributed parameter model of double-pipe heat exchanger with its spatial discretization based on orthogonal collocation method. This approach preserves the distributed parameter nature and nonlinearities of the unit with relatively low numerical complexity and high modeling accuracy. For the suggested model, the tuning procedure is suggested and modeling accuracy is validated for realistic experimental measurement data. The stability of the model (both structural and numerical) is addressed and sensitivity analysis and comparison with finite difference approximation are presented. The results show that the suggested modeling and tuning method is useful for practical applications.

Plate Heat Exchangers – Flow Analysis through Mini Channels

The study presents a Computational Fluid Dynamics (CFD) numerical study for two different models of mini channels, included in plate heat exchangers structure. The influence of geometric characteristics of the two studied plates on the intensification process of heat transfer was studied comparatively. For this purpose, it was examined the distribution of velocity, temperatures fields and distribution of convection coefficient along the active mini channel. The analyzed mini channels had the inclination angles of 30° respectively 60° and the Reynold flow number was 3500. Also a session of experimental measurements have been carried out on the two types of analyzed plates for the heat exchangers, confirming the results obtained through numerical simulation that the plate heat exchanger model using mini channels with inclination angle of β = 60° provides best heat transfer.

Performance and flow distribution of the plate heat exchanger with supercritical fluid of carbon dioxide

The present study proposes a plate heat exchanger model that is capable of simulating the supercritical fluids like CO2. The plate heat exchanger is of U-type configuration, and the size of the plate is 600 mm wide and 218 mm in height. Simulations are carried out for both isothermal and nonisothermal cases with water-to-water and water-to-CO2 plate heat exchanger. The proposed model was first compared with some existing water-to-water plate heat exchanger data. Generally, the predicted water flow distributions are in line with the experimental data. Yet the simulation results of temperature distribution alongside the plate agree excellently with other predicted model. For the water side distribution within the plate heat exchanger, it is found that a detectable mal-distribution prevails and the flowrate shows a consistent decline from the first to the last plate. Basically, a larger mal-distribution is seen when the inlet flowrate is increased or when the plate number is increased. The simulation indicates that the inlet temperature of water casts negligible influence on the water flowrate distribution. By contrast, it is found that the inlet temperature difference for the CO2 side may raise significant changes of thermodynamics andtransport property of CO2, and result in a great difference in flow distribution. Generally the maldistribution of the CO2 is much less severe due to more even pressure difference between the intake and exhaust manifold. The effect of pressure on heating capacity for the water-CO2

The influence of plate corrugations geometry on plate heat exchanger performance in specified process conditions

The mathematical model of plate heat exchanger (PHE) is developed using decomposition of the plate on its main corrugated field, which cause major effect on heat transfer, and distribution zone, which influences mostly the hydraulic performance. Model is validated on experimental data for some commercial plates. It is shown, that for specified pressure drop, temperature program and heat load the geometrical parameters of plate and its corrugations, which are enable to make PHE with minimal heat transfer area, can be found. The developed mathematical model can be used for designing of plates with geometry, which is in the best way satisfying process conditions of the certain specific range. The case study for conditions of PHE application in District Heating systems is presented.

3‐D Milk Fouling Modeling of Plate Heat Exchangers with Different Surface Finishes Using Computational Fluid Dynamics Codes

ABSTRACTMilk fouling and self‐cleanability of the heat exchanger surface during the pasteurization process has gained attention from industries as well as academia. In particular, the antifouling mechanism associated with plate corrugation profiles causing the extreme turbulent flow scheme and surface coatings to reduce the surface energy is uncertain. This study was aimed to develop a computational fluid dynamics (CFDs) model in three‐dimensional (3‐D) environment, which could estimate antifouling performances of plate heat exchangers (PHEs) during milk pasteurization process. It was the first attempt to simulate the fouling and temperature distribution patterns on realistic corrugated surfaces of PHE unit with different surface treatments. The conventional stainless steel surface and stainless steel plates coated with Lectrofluor 641 and graded Ni‐P‐polytetrafluoroethylene were compared for their antifouling performances. A transient 3‐D fouling model was developed based on heat and mass transfer equations, and fouling kinetics involving diffusion and protein adhesion mechanisms. Pattern and size of corrugations of actual PHE were measured and subsequently used to build 3‐D solid geometry using AutoCAD (Autodesk, San Rafael, CA). The geometry file was meshed using Gambit software (Fluent Inc., Lebanon, NH) and further transferred to CFD codes. Fouling predictions based on chemical kinetics and the temperature‐dependent parameters accounting for different surface energy values were close to experimental data within a maximum prediction error of 7%. The developed 3‐D fouling model is expected to meet the demand of food industries to correlate the surface energy with the self‐cleanability of food thermal process equipments and seek the theoretical solution.PRACTICAL APPLICATIONSMilk‐fouling phenomena of plate heat exchangers (PHEs) result in an increase of energy consumption, extra maintenance, higher labor costs and a decrease in the productivity. In addition, fouling deposits can cause the growth of unwanted microorganisms on the corrugated surfaces of PHEs. In this study, the transient three‐dimensional computational fluid dynamics model was developed to describe fouling phenomena in consideration of realistic corrugation profiles and estimate the amount of surface fouling based on the hydrodynamic and thermodynamic performances of the PHEs and surface characteristics (conventionally uncoated stainless steel [SS‐316] and stainless steel surfaces with Lectrofluor 641 and graded Ni‐P‐polytetrafluoroethylene).

Combined Experimental and Simulation (CFD) Analysis on Thermal Performance of Plate Heat Exchanger Using Kerosene as Working Fluid

The plate heat exchanger exhibits excellent heat transfer characteristic, which allows a very compact design with ease of maintenance and modification of heat transfer area by adding (or) removing plates. Constructional parameters such as flow path, trough angle and corrugation can affect the performance of plate heat exchangers by altering effectiveness (?) and number of transfer unit (NTU). Especially plate heat exchangers play a vital role in petroleum industries for wide range of temperature application. Hence, it was proposed to choose kerosene as cold fluid and hot water as hot fluid in this present investigation. A vertical type of plate heat exchanger, in which flow pattern is maintained as co-current, has been used to conduct the experimental runs. The numbers of plates in the plate heat exchanger used in the present study are 10. The number of flow channels (space maintained between two consecutive channels) allocated for both fluids are 9. Experimental runs have been conducted for different combinations of hot fluid flow rates and cold fluid flow rates for single phase flow, in which hot water is considered as hot streams and kerosene as cold fluid. The thermal performance of plate heat exchanger has been analyzed based on calculated parameters using experimental data set. A similar corrugated plate heat exchanger model having the same dimensions as that of the experimental one was developed with aid of CFD tool. The model was simulated at different operating conditions and compared with experimental results. The simulated results are in good agreement with experimental data. The percentage deviation between experimental results and simulation results for over all heat transfer coefficient is less than ±6%.