Conventional Plate Heat Exchanger Research Articles

Flow and heat transfer characteristics and comprehensive evaluation of asymmetric plate heat exchangers for centralized heat supply

The structure of flow channel on both sides of the conventional plate heat exchanger(CPHE) is symmetrical. CPHEs are struggle to perform efficiently when subjected to asymmetric working conditions in district heating system. In order to improve the performance of plate heat exchangers under asymmetric conditions, asymmetric plate heat exchangers(APHEs) was designed. In this paper, APHEs were parameterized by asymmetric factor a. An evaluation index η for APHE is introduced to quantitatively analyze APHE’s suitability in district heating system. Numerical simulations were performed to investigate the heat transfer characteristics and resistance characteristics of the APHEs with 11 asymmetric factors a. Through using η, APHEs with the best comprehensive performance were found, when the flow ratio is 1.50, 1.75, 2.00, 2.25, 2.50 and 2.75. In flow ratio, APHEs provide the comprehensive performances with an improvements of 28 %, 39 %, 54 %, 65 %, 72 % and 83 % compared with CPHEs. Correlations equation for the average Nu and f on both hot and cold sides of the APHEs were established. There exists a correlation between Nu and f for the APHEs with respect to asymmetry factor a and flow ratio.

Performance assessment of novel catalytic spouted-bed vapor jet flow heat exchanger in amine-based carbon capture process

This study introduced a spouted bed and jet flow catalytic heat exchanger (SBJ-EX). This novel non-agitated technology can potentially integrate with a conventional desorption column to enhance heat transfer and CO2 desorption performance in amine-based post-combustion carbon capture systems. As its first research in the carbon capture field, this work experimentally evaluated key factors including overall heat transfer coefficient, logarithmic mean temperature difference, temperature distribution along the reactor, and cyclic loading under varied parameters such as inlet temperature of the heating oil, inlet solvent temperature, rich CO2 loadings, and mass of catalysts to simulate real-world operating conditions using benchmark MEA solvent and solid acid catalyst HZSM-5. Compared to conventional plate heat exchangers, the SBJ-EX demonstrated over a 70 % enhancement in heat transfer performance due to its effective overall heat transfer coefficient. It also exhibited impressive CO2 desorption performance even at lower temperatures with sufficient catalysts. Unlike agitated-type heat exchangers, the SBJ-EX could minimize catalyst attrition and offer more excellent stability. In contrast to fixed-bed catalyst desorbed columns, this equipment offered a more compact design for quicker and simpler catalyst replacement to reduce downtime for operators significantly. The SBJ-EX can also function as an optional backup or add-on unit to provide operators with flexibility. This work further discussed advantages and challenges of the SBJ-EX operation. This work enriched the future research outlook for this technology, and contributed a commercially viable approach to catalysts in carbon capture processes.

Design and numerical assessment of an additively manufactured Schwarz diamond triply periodic minimal surface fluid-fluid heat exchanger

In aerospace, thermal applications demand compact, lightweight, and efficient heat exchangers. Additive manufacturing processes offer the potential to create highly complex structures that are not achievable through traditional manufacturing methods. This work presents the development of an additively manufactured fluid-fluid heat exchanger that shows the potential to enhance the performance, reduce weight, and increase compactness compared to a conventional plate heat exchanger. A numerical model of the conventional plate heat exchanger was created, and fluid dynamics simulations with heat transfer were performed. Validation of the simulations was done by experiments. Then, a novel heat exchanger was designed using a bottom-up approach and investigated at different levels of complexity using computational fluid dynamics. The internal structure of the final heat exchanger consists of a repeating triply periodic Schwarz diamond minimum surface elongated in the direction of flow. The heat exchanger was manufactured with laser powder bed fusion process using AlSi10Mg. It had a 108% higher compactness and 54% lower weight compared to the plate heat exchanger. Numerical analysis yielded the pressure loss in pascal was reduced by 50%–59% while heat transfer in watts was improved by 3%–5%. Future researches should experimentally investigate the thermal and fluid mechanical characteristics of the novel additively manufactured heat exchanger and increase compactness and heat transfer further by analyzing the minimum partition wall thickness and the impact of wall roughness and deposit formation.

Study of Particulate Fouling Inhibition Characteristics on a Novel Composite Coating

Particulate fouling is a common fouling in heat exchange equipment, it causes tube corrosion and increases flow resistance. Particulate fouling increases the hidden danger of equipment and requires high treatment costs. In this paper, a novel Ni−P−TiO2 composite coating is prepared on 316 stainless steel using electroless plating and the fouling inhibition characteristics of the novel composite coating are studied using a dynamic monitoring experimental system. The experimental results show that the fouling thermal resistance of the Ni−P−TiO2 composite coating is obviously lower than that of 316 stainless steel under the same working conditions. With the increase in cooling water velocity and inlet temperature, the surface fouling thermal resistance decreases, while, with the increase in particle concentration, the fouling thermal resistance increases. Based on DLVO theory, it is found that the surface energy of Ni−P−TiO2 composite coating is close to the best surface energy for inhibiting particulate fouling deposition, which can significantly inhibit particulate fouling deposition. Compared with the stainless-steel surface of a conventional plate heat exchanger, the Ni−P−TiO2 composite coating not only inhibits the accumulation of particulate fouling, but also reduces the adhesion strength of particulate fouling; additionally, the fouling is easier to strip off the heat exchange surface, which realizes the lasting and efficient fouling inhibition on the heat exchange surface. The research results can provide a data reference for the fouling inhibition design and daily efficient operation of heat exchangers.

Experimental and numerical study on the heat transfer and flow characteristics of convex plate heat exchanger based on multi-objective optimization

The convex plate heat exchanger is one of the new types of plate heat exchangers that have specific functional properties compared to conventional plate heat exchangers, the structural parameters of convex plate heat exchangers are important in affecting the heat transfer performance. In this paper, based on two-layer multi-objective optimization which is aimed at maximum performance evaluation criterion (PEC) and maximum field synergy number (Fc), the heat transfer and flow characteristics of convex plate heat exchanger are investigated experimentally and numerically. The optimization findings are broken down into single factor, response surface, and sensitivity analysis. The optimal results under different objective functions are analyzed and the optimal structural parameters obtained which are the welding hole radius (R) is 5.81 mm, the ellipse radius (L) is 5.02 mm, and the welding hole spacing (P) is 64.00 mm; Compared to the structure before optimization, the size-optimized structure may enhance the temperature differential between the inlet and outflow of the cooling water by less than 8.27%, the heat transfer performance is increased by 20.43%, and the comprehensive performance is improved by 2.3∼19.59%.

Process design and analysis of a flexibly adjusted zonal absorption heat exchanger for high-rise building heating systems

• A flexibly adjusted zonal absorption heat exchanger is proposed. • It can realize the function of independent heat supply in each zone. • The heat exchange efficiency under the design condition reaches 1.268. • The system has symmetry for the heat supply of each zone. • The zonal absorption heat exchanger has excellent flexible adjustment ability. In terms of the high-rise buildings with large areas, the heating system of the vertical zone is generally considered to solve the problems of hydraulic imbalance and bearing pressure. On the basis of the conventional plate heat exchanger, a flexibly adjusted zonal absorption heat exchanger utilized in the heating station for high-rise buildings is proposed in this paper. This system can realize the function of the zonal plate heat exchanger and the absorption heat exchanger at the same time. Under the conventional design condition, this system can reduce the outlet water temperature of the primary network to 17.4 K lower than the inlet water temperature of the secondary network. The heat exchange efficiency of the AHE reaches 1.268. The low water outlet water temperature of the primary network contributes to the waste heat recovery and improves the heating capacity. Moreover, the system has excellent heat load adaptability and adjustment ability under the partial load. The heat load rate of different zones decreases in the same proportion at the partial load condition. When the flow rate of the primary network decreases to 25% of the design value, the difference of the heat load rate in different zones is only 1.7%. The results contribute to the energy conservation in zonal heating systems.

Comparison of flow resistance and port maldistribution between novel and conventional plate heat exchangers

Corrugated plate heat exchanger (CPHE) is the most utilized compact heat exchanger (HE) due to its high thermal performance. The present study is conducted for modified CPHEs with chevron angles β = 60°/60° and 30°/30°, and for conventional CPHE with β = 30°/30°. The characteristics of flow resistance along with other important physical parameters inside the modified and the conventional CPHEs are presented in this study. Acomputational Fluid Dynamics (CFD) approach is employed to conduct the present study, where realizable k − ε turbulence model is used. The numerical simulations results are validated against available experimental data in the literature. The overall thermal performance is examined by calculating the ratio of the heat transfer rate to the ratio of increase in the pumping power (JF factor). The core pressure drop, fanning friction factor (f), turbulence kinetic energy (TKE), and port maldistribution have been investigated. The findings are compared against those of conventional CPHE with β = 60°/60°. The modified and the conventional CPHEs are alike in geometrical and physical tests conditions. The simulations are performed for single-phase (water-water), counter-current flow, and for a range of Reynolds number (Re = 500 to 2000). The results show that f data of the modified CPHEs are ~4.5–7 fold higher than those of the conventional CPHEs. The data of port maldistribution of conventional CPHEs are found up to ~8 times greater than those of the modified ones. The TKE of the modified CPHEs is found ~2–3 times higher than those of the conventional ones. In addition, due to the high pumping power requirements of the modified CPHEs, their JF data have been found 1.1–1.5 fold lower than those of the conventional CPHEs. The f correlations of the modified and the conventional CPHEs have been established.

Mechanical Integrity Assessment of Two-Side Etched Type Printed Circuit Heat Exchanger with Additional Elliptical Channel

Printed circuit heat exchangers (PCHEs) are often subject to high pressure and temperature difference between the hot and cold channels which may cause a mechanical integrity problem. A conventional plate heat exchanger where the channel geometries are semi-circular and etched at one side of the stacked plate is a common design in the market. However, the sharp edge tip channel may cause high stress intensity. Double-faced type PCHE appears with the promising ability to reduce the stress intensity and stress concentration factor. Finite element analysis simulation has been conducted to observe the mechanical integrity of double-etched printed circuit heat exchanger design. The application of an additional ellipse upper channel helps the stress intensity decrease in the proposed PCHE channel. Five different cases were simulated in this study. The simulation shows that the stress intensity was reduced up to 24% with the increase in additional elliptical channel radius. Besides that, the horizontal offset channels configuration was also investigated in this study. Simulation results show that the maximum stress intensity of 2.5 mm offset configuration is 9% lower compared to the maximum stress intensity of 0 mm offset. This work proposed an additional elliptical upper channel with a 2.5 mm offset configuration as an optimum design.

Numerical simulation and experimental research on heat transfer and flow resistance characteristics of asymmetric plate heat exchangers

The asymmetric plate heat exchanger (APHE) has the possibility of achieving balanced pressure drops on both hot and cold sides for situations with unbalanced flow, which may in turn enhance the heat transfer. In this paper, the single-phase water flow and heat transfer of an APHE consisted of two types of plates are numerically (400⩽Re⩽ 12000) and experimentally (400⩽Re⩽ 3400) investigated. The numerical model is verified by the experimental results. Simulations are conducted to study the effects of N, an asymmetric index proposed to describe the geometry of APHEs. The correlations of the Nusselt number and friction factor in the APHEs are determined by taking N and working fluids into account. It is found that an optimal Nexists where the pressure drops are balanced and the heat transfer area reaches the minimum. The comparison between heat transfer and flow characteristics of the APHEs and the conventional plate heat exchanger (CPHE) is made under various flow rate ratios of the hot side and the cold side and different allowable pressure drops. The situations under which APHE may perform better are identified based on a comprehensive index Nu/f1/3.

A study on development of the thermal storage type plate heat exchanger including PCM layer

Thermal storage type plate heat exchanger (TSPHEs) was newly developed in the process of research a heat pump using industrial waste heat as a heat source for evaporation. A conventional plate heat exchanger is a structure in which two media perform heat transfers through a separation plate. However, TSPHEs have a structure in the basic structure of conventional plate heat exchanger adding the PCM layer filled to phase change material. Therefore, the TSPHEs performed heat exchange between three heat media (hot water-cold water-PCM). The thermal energy supplied through the hot water is mainly transferred to the cold water and some of it is transferred to the phase change material filled in the PCM layer. When if the hot water is shut down and the heat source can’t be supplied, the heat stored in the PCM layer is transferred to the cold water through the hot water, the medium of transmission. In the article, using the e-NTU method, a thermal equilibrium equation is established between the three heats media used in the TSPHEs. Based on the established theoretical formula, the relationship between total overall heat transfer coefficient and e, S (temperature differential), and Cr (heat capacity ratio) was obtained. In addition, the validity of the theoretical analysis was demonstrated through the experimental method and compared with the correlation of the existing overall heat transfer coefficient. The results of this article will be utilized as basic data for the design of the TSPHEs, and will be used to predict the amount of heat exchange and thermal storage capacity of the TSPHEs.

Numerical investigation of thermal and hydraulic performance of shell and plate heat exchanger

Detailed single-phase performance of the shell and plate heat exchangers is presented in this study with corresponding chevron angles (β) of 45° and 75°, respectively. Unlike those conventional plate heat exchanger, the thermofluids characteristics perform quite differently between shell and inner channel. For a larger chevron angle (75°), the friction factor is comparable amid shell and inner channel. Yet the friction factor in the shell channel is much lower than that in inner channel at a smaller chevron angle (45°). The shell channel contains more unidirectional flow pattern while some flow re-circulation may occur at the entrance/exit port of the inner channel. The flow pattern and temperature distribution in the shell channel are generally more uniform than those in inner channel. The shell channel with β = 45° shows a better overall performance for its much lower friction factor when the Reynolds number is low. The heat transfer performance for shell channel exceeds the inner channel appreciably when the chevron angle is high (75°). The heat transfer performance depends on the corrugation aspect ratio, and an optimum ratio is derived. For the inner channel, the optimum value is around 0.75 while it is 0.53 for the shell channel.

Evaluation the effects of geometrical parameters on the performance of pillow plate heat exchanger

The growing demand for energy-saving in industries has led to numerous researches to improve the heat exchangers thermal performance in a variety of methods. The pillow plate heat exchanger (PPHE) is one of the new types of plate heat exchangers that have specific functional properties compared to conventional plate heat exchangers. The objective of the present investigation is providing comprehensive information about effective geometrical parameters of PPHEs for optimal design. In the present study, the performance of PPHEs is studied by numerical simulation. The obtained results have shown that the geometrical parameters of the PPHEs have a significant effect on thermal performance. The considered geometrical parameters include the height of pillow plate channels, and the longitudinal and transversal distance of welding spots. The heat exchanger thermal performance increases by expanding the height of the pillow channel mostly at low Reynolds number. After increasing longitudinal and transversal distance of welding spots the heat transfer and friction factor decreases in both cases. However, the effect of friction factor decrement on heat exchanger performance is more than decreasing in heat transfer. Thereby the PPHE with longer longitudinal or transversal distance of welding spot is efficient.

Investigation on operation strategy of absorption heat exchanger for district heating system

The absorption heat exchanger (AHE) combined by an absorption heat pump (AHP) and a plate heat exchanger (PHE) is invented for replacing conventional plate heat exchangers at the heating substation in the district heating system, which could decease the return water temperature of primary pipe (PP) significantly when compared with the conventional PHE. The return water temperature of PP is much lower than that of secondary pipe (SP) in the AHE without consuming extra energy. The heating capacity of an original heating pipe is increased obviously, and it is much more convenient to recover different kinds of low grade industrial waste heat by the low temperature return water of PP. Meanwhile, inlet and outlet temperatures of PP and SP vary obviously during a whole heating period, therefore, the effect on heat exchange process caused by the LiBr (lithium bromide) solution circulating rate and the ratio of flow rates of PP and SP in the PHE is studied, which could ensure optimal performance of AHE under different working conditions. Operation regulation curves are given for regulation of the AHE during the whole heating period.

Thermal performance of brazed metalfoam-plate heat exchanger as an evaporator for organic Rankine cycle

Compact-sized organic Rankine cycle (ORC) power generators call for higher performance and down-sized heat exchangers. Heat exchangers in ORC systems, especially evaporators contribute to a big portion of the system size as well as the capital cost, and their price is also directly related to their size. Since the heat transfer area plays a direct role in the performance of heat exchangers, high-porosity metal foams are proposed for insertion into heat exchanger channels to enhance the heat transfer mechanism in evaporators. Their high surface area to volume ratio makes them a good candidate for manufacturing high-performance heat exchangers. The metalfoams are being considered to improve performance while keeping the size of heat exchangers small. In this experimental study, the performance of a 100 kW class heat exchanger with the channels brazed with nickel based metal foam and stainless steel sheets was investigated. A hot water loop was designed for heat input. The cold side of the heat exchanger works with R245fa as the working fluid. The phase-change heat transfer experiments were performed with different mass flow rates ranging from 0.32 to 0.51 kg/s while the operating pressure was at 10 to 13 bar with hot water inlet temperature was 133℃. Furthermore, the heat transfer performance is compared with a commercial plate heat exchanger (produced by Alfalaval, AC120EQ) which was custom-made as a 100kW class evaporator. In the comparison test, refrigerant side has 0.5kg/s of mass flow rate at 44℃ and heat source side has 1.23 kg/s mass flow rate at 132℃. Although the pressure drop in the metal foam plate heat exchanger is increased compared to that of the conventional plate heat exchanger, increase of the recovered waste heat from the heat source is much higher due to higher overall heat transfer coefficient. As a result, the energy density of the new heat exchanger is about 2.5 times higher than that of the conventional plate heat exchanger.

Experimental studies on a direct-steam-generation absorption heat transformer built with vertical falling-film heat exchangers

This study presents an experimental rig of direct-steam-generation single-stage heat transformer (SSHT), which was built with four main vertical heat exchangers and a plate heat exchanger. This rig uses a LiBr-water binary working fluid and is driven by low-grade hot water. Data from six test runs were analysed. The results show that bilateral falling film made it easier for the absorber to generate steam directly with pressure changing from 190kPa to 260kPa, which corresponded to an absorber heat load from 15.5kW to 7.2kW, coefficient of performance (COP) from 0.38 to 0.20, and exergy coefficient of performance (ECOP) from 0.48 to 0.27, respectively. The absorber temperature can be as high as 124°C, with calculated internal gross temperature lift (GTL) of 34.8K and external GTL of 29.6K. The economizer was a conventional plate heat exchanger with effectiveness around 0.73 in six test runs.

Analysis of Heat Transfers inside Counterflow Plate Heat Exchanger Augmented by an Auxiliary Fluid Flow

Enhancement of heat transfers in counterflow plate heat exchanger due to presence of an intermediate auxiliary fluid flow is investigated. The intermediate auxiliary channel is supported by transverse conducting pins. The momentum and energy equations for the primary fluids are solved numerically and validated against a derived approximate analytical solution. A parametric study including the effect of the various plate heat exchanger, and auxiliary channel dimensionless parameters is conducted. Different enhancement performance indicators are computed. The various trends of parameters that can better enhance heat transfer rates above those for the conventional plate heat exchanger are identified. Large enhancement factors are obtained under fully developed flow conditions. The maximum enhancement factors can be increased by above 8.0- and 5.0-fold for the step and exponential distributions of the pins, respectively. Finally, counterflow plate heat exchangers with auxiliary fluid flows are recommended over the typical ones if these flows can be provided with the least cost.

Optimization of novel heat exchanger design for the application to low temperature lift heat pump

The low temperature lift heat pump (LTLHP) utilizes a small difference between the condensing and evaporating temperatures of a working fluid. It requires a larger heat transfer area, a higher volume flow rate, and a higher temperature of heat source fluid, as compared to the typical heat pump system. In order to improve the performance of conventional plate heat exchangers, a novel heat exchanger with new geometries has been developed for application in the LTLHP. The main design development strategies were regulating the flow area ratio and offsetting plates in order to balance the heat transfer and pressure drop of the heat exchanger. The design parameters of the novel heat exchanger design were optimized with multi-scale approaches. Once the refrigerant-side geometry is properly designed according to the water-side performance, the overall heat transfer capacity of the novel heat exchanger is predicted to be higher than that of PHX by 53–204%. This can decrease the cost of the heat exchanger and increase the performance of the LTLHP system.

Performance enhancement of a thermally activated cooling system using microchannel heat exchangers

In the current study a thermally activated cooling system that combines an ORC system with a vapor compression cooling cycle was developed and tested under laboratory conditions. This combined system can utilize waste heat or other thermal sources such as solar and geothermal to generate power and cooling. Hot oil with temperature up to 200 °C was used as the simulated heat source for its convenience. Microchannel heat exchangers were used throughout the system in order to meet the performance, size and weight challenges. Two conventional plate heat exchangers for the boiler and recuperator were also tested inside the system for comparison purposes. Compared to the plate boiler and recuperator, the integrated microchannel boiler/recuperator displayed significant improvement of the heat transfer effectiveness over the range of mass flow rates examined which translates to higher conversion efficiency and overall COP. A simplified model, used to design the microchannel recuperator, ignores the entrance and conjugate heat transfer effects, but it appears to match well the trend of measured average heat transfer coefficients for all cases tested. After taking into account the channel side walls, the measured values of the average heat transfer coefficient agree also with the predicted one. Because of this relatively conservative design approach, the actual heat transfer effectiveness for the recuperator was significantly higher than the designed value of 85%. With the integrated microchannel boiler/recuperator, this thermally activated cooling system was able to achieve over 5 kW of cooling and approached an overall COP of 0.8 under laboratory conditions.

Improvement of the Fresh Taste Intensity of Processed Clementine Juice by Separate Pasteurization of its Serum and Pulp

This work describes a process to separate the Clementine juice by centrifugation into two fractions, the larger one (`serum fraction') almost lacking of pulp, and the smaller one (`pulp fraction') enriched in pulp, which are independently pasteurized in conventional plate heat exchangers under different conditions. Both fractions were aseptically blended giving a final product, whose fresh taste did not differ from that of the initial nonheated juice. The larger serum fraction was almost free of pectin methylesterase activity and could be pasteurized under minimal heat conditions, just enough to destroy microorganisms, less heat-resistant than enzymes. Since only a minor part of the juice (the pulp fraction) received the usual heat treatment, fresh taste was preserved. Destruction of Lactobacillus plantarum inoculated to the serum fraction was fitted accurately by the Weibull model, with a reduction higher than 5 log cycle at 57.5 °C for 20 s and no counts were found at 60 °C for 10 s. According to this, thermal treatment of the serum fraction (78% of the initial juice) was fixed at 60 °C for 15 s. Sensory evaluation of fresh taste intensity showed no significant differences between serum treated at 60°C for 15 s and fresh serum. The pulp fraction (22%) was pasteurized at 85 °C for 15 s and at 90 °C for 30 s to assure enough enzyme inactivation. No differences were found between the nonpasteurized juice and the blend of pulp and serum pasteurized as explained above, whereas both samples presented fresher taste than the whole juice treated at 90 °C for 30 s.

Evaporation Performance of a Plate Heat Exchanger Embossed with Pyramid-Like Structures

A new plate heat exchanger for water-refrigerant systems such as chillers has been developed. Plates embossed with pyramid-like structures were stacked up to form the heat exchanger. The measured heat transfer coefficients of the plates (convective vaporization) were about one and a half to two times higher than those of commercial herringbone-type plate heat exchangers. The measured heat transfer coefficient for water convection was comparable to the values for conventional plate heat exchangers. We also found that the plate surface with pyramid patterns made the plate heat exchanger more compact or reduced the pressure drop on the water side.