Brazed Plate Heat Exchanger Research Articles

Effect of end plates on heat transfer of plate heat exchanger

Steady-state heat transfer data for single-phase (water) in both frame-and-plate (FPHE) and brazed plate heat exchangers (BPHE) are presented with various number of chevron plates in U-type flow arrangement. Analysis of the experimental results indicates that the end plates, instead of being adiabatic, function as fins due to the contact between adjacent plates. The experimental data is used to validate a thermal conduction model in ANSYS, which indicates that the end plates fin efficiency is a function of fluid convective heat transfer coefficient and conductive thermal resistance. In the FPHE, the pressing force of the frame may affect the contact thermal resistance, thus change the fin efficiency. In BPHE, the fin efficiency is much higher due to the larger contact area and higher conductivity of the brazing material. Although the effect of end plates is quickly diluted by the increased number of plates in real applications, it could be significant when plate number is small, as is often the case in laboratory settings for the development of heat transfer correlations.

Experimental development and bond graph dynamic modelling of a brazed plate heat exchanger

This article is devoted to the dynamic study of a brazed plate heat exchanger (BPHE). First, an introduction to the industrial context of the current FUI THERMOFLUIDE project is proposed. A succinct presentation of the heat exchanger technology is proposed. Afterward, a state of the art discussion of BPHE modelling, heat transfer and pressure drop correlations is given. Then a detailed mathematical description of an original dynamic model is presented. The last section deals with a description of the experimental test rig and performed validation tests.

Experimental development and bond graph dynamic modelling of a brazed plate heat exchanger

Experimental development and bond graph dynamic modelling of a brazed plate heat exchanger

Heat transfer correlations for single-phase flow in plate heat exchangers based on experimental data

In the present paper, the single-phase heat transfer for nine brazed-plate heat exchangers with different geometric parameters is experimentally investigated. An ethylene glycol and water mixture is used as working fluid. First, the results show that the herringbone angle is the most dominant factor influencing heat transfer. Then, the results also show that geometric dimensions affect heat transfer jointly with herringbone angle. Individual correlations and a general correlation based on experimental data are presented. Then the empirical equations are compared to existing correlations from the open literature. Based on archival data and the experimental data presented in this work, a generalization of single-phase heat transfer performance of plate heat exchangers is given, relating the Nusselt number to heat exchanger geometry, Reynolds number, and fluid properties. The proposed correlation is based on experiments of 22 heat exchangers and 25 empirical correlations, and the percent root-mean-square deviation is 20.77%. This novel correlation has the accuracy of 50% and it is applicable for a very large range of plate heat exchangers.

Performance studies on a domestic refrigerators retrofitted with building-integrated water-cooled condenser

Residential buildings contribute to the greenhouse gas emissions through the use of energy-intensive products. Household energy consumption and associated emissions can be reduced partly if energy-saving methods are adopted by the occupants. This paper studies the performance of domestic refrigeration system with water-cooled condenser in which the water used for general purposes in a residential building has been considered as the cooling water for the condenser. The circulation quantity of water per day has been varied, and the variation of COP has been studied and presented. The results obtained from the theoretical and experimental studies show that the COP of the system with brazed plate heat exchanger (BPHE) as water-cooled condenser is 57% to 75% higher than that of air-cooled condenser. Moreover, the system with water-cooled BPHE reduces the per day energy consumption of the system from 21% to 27%. The TEWI of the system with water-cooled BPHE is also 5% to 43% lower than that of the system with air-cooled condenser, and thus the building energy-efficiency could be improved by integrating the refrigerator with the general water supply of a residential building.

A review on in-tube two-phase heat transfer of hydro-fluoro-olefines refrigerants

Since 2010, hydro-fluoro-olefines have been experimentally studied during both boiling and condensation with the research productions continuously growing. At a glance, most of the data collected regards the two most available fluids, R1234yf and R1234ze(E), which were tested during two-phase flow both inside and outside smooth and microfin tubes or in brazed plate heat exchangers, as well on other different enhanced surfaces. A few data were obtained with noncommercially available hydro-fluoro-olefines, such as R1234ze(Z). In addition, relevant work has been dedicated to study the heat transfer capabilities of hydro-fluoro-carbon/hydro-fluoro-olefine mixtures. This article presents a critical review on the published research articles on in-tube two-phase heat transfer during boiling and condensation of hydro-fluoro-olefine refrigerants. In particular, a large database of experimental measurements was collected, reviewed, discussed, and then compared against common models to identify the most suitable for all the investigated two-phase heat transfer processes.

Experimental Analysis of Heat Transfer and Friction Factor in Plate Heat Exchanger with Different Orientations Using Al2O3 Nanofluids

Experimental investigations has been done to find out the heat transfer characteristics and friction factor of water based Al2O3 nanofluids as a coolant in brazed plate heat exchanger. Plate heat exchanger either use horizontally or vertically. The base plate of the plate heat exchanger was kept inclined at (0⁰, 30⁰ ,60⁰, 90⁰). The experimentation have been done on the two different concentration of the nanofluids (0.1 v/v% and 0.2 v/v%). It was observed that the heat trasnfer characterstics improves with increase in Reynolds number. It has been studied that nanofluids in a plate heat exchanger has maximum of 34% heat transfer rate over the base fluid. It has been observed that from horizontal to vertical heat transfer rate decreases with increase in Reynolds number. Results shows that there is (10-15) % has been found out when the base plate of plate heat exchanger made inclined from horizontal to 30⁰ of inclination.

Exergy analysis of a domestic refrigerator with brazed plate heat exchanger as condenser

Domestic refrigeration system is one of the major energy-consuming devices. Improving its energy and exergy efficiencies plays a vital role in the energy conservation strategies on domestic energy sector. One of the methods to improve the performance is the replacement of existing components and operation of the system in low condensing pressure. Therefore, in this work, the conventional air-cooled condenser has been replaced with water-cooled brazed plate heat exchanger. Besides the COP, exergy efficiency and irreversibility in all the basic components of a 190-L domestic refrigerator have been studied. The experimental results show that the COP and exergy efficiency of the proposed system are 52–68 and 46–55 %, respectively. This is higher than that of the conventional system. Moreover, the irreversibility of the proposed system is 34 % less than that of the conventional system, and the exergy efficiency of HC mixture is 4–7 % higher than R134a under similar operating conditions.

Heat transfer in plate heat exchanger channels: Experimental validation of selected correlation equations

Abstract This study is focused on experimental investigation of selected type of brazed plate heat exchanger (PHEx). The Wilson plot approach was applied in order to estimate heat transfer coefficients for the PHEx passages. The main aim of the paper was to experimentally check ability of several correlations published in the literature to predict heat transfer coefficients by comparison experimentally obtained data with appropriate predictions. The results obtained revealed that Hausen and Dittus-Boelter correlations underestimated heat transfer coefficient for the tested PHEx by an order of magnitude. The Aspen Plate code overestimated heat transfer coefficient by about 50%, while Muley-Manglik correlation overestimated it from 1% to 25%, dependent on the value of Reynolds number and hot or cold liquid side.

An experimental study on the thermal and fouling characteristics in a washable shell and helically coiled heat exchanger by the Wilson plot method

Brazed plate heat exchangers (BPHEX) are broadly used in water source heat pump systems for their large heat transfer capacity. Despite their high heat transfer rate, their high-performance rate tends to decrease sharply, due to fouling and they cannot be cleaned. So the thermal and fouling resistances of washable Shell and helically coiled tube heat exchangers (SCHEX) are designed and experimentally investigated in this study. Heat exchangers with two different tube types are studied and compared with a brazed plate heat exchanger. The overall thermal resistance coefficient of the heat exchangers as determined by using Wilson plots is 38% lower than that of the brazed plate heat exchanger at a Reynolds number of 2460. Fouling test results revealed that regular maintenance and physical cleaning can be used to maintain the thermal resistance of fouling of the washable heat exchanger at a level equal to or less than that of the brazed plate heat exchanger.

Experimental studies on domestic refrigeration system with brazed plate heat exchanger as condenser

In view of Kyoto protocol, there is a pressing need to reduce the energy consumption and environmental impacts of domestic appliances. In the total energy consumption of household appliances, domestic refrigerator plays a vital role. Alternate refrigerants and improvement in the performance of the components can contribute to tackle the above issue in a domestic refrigeration system. In this paper, the performance of a domestic refrigeration system with brazed plate heat exchanger as condenser, and working with refrigerants such as R290/R600a and R134a was studied using experimental method. The result showed that the system with water-cooled brazed plate heat exchanger reduces the per day energy consumption of a system from 21% to 27% and increases the COP from 52% to 68%, when compared to conventional system. The compressor discharge temperature and dome temperature are also dampened. For R134a and R290/R600a, the TEWI of the system with water-cooled brazed plate heat exchanger is lower than that of the system with air-cooled condenser by 26.8% and 21%, respectively. Among the refrigerants, R290/R600a showed higher performance than R134a.

Flow boiling of R32 inside a brazed plate heat exchanger

This paper presents measurements of heat transfer coefficient obtained during flow boiling of R32 inside a brazed plate heat exchanger (BPHE). Although R32 is known as a very interesting refrigerant for its thermodynamic and thermophysical properties, very limited flow boiling data are published in the open literature for R32 working in brazed plate heat exchangers.The present experimental data are measured to investigate the effect of refrigerant heat flux, mass velocity, inlet vapor quality and superheating at the outlet. The saturation temperature is kept constant at around 5 °C, which is a usual temperature level for evaporation in liquid coolers. As a significant result, differently from other studies on flow boiling with HFC refrigerants, mass flux is found to be very important, meaning a high contribution of the convective term on the heat transfer coefficient.The present data are also analyzed to assess available correlations for flow boiling inside BPHEs, in order to provide useful information on the accuracy of predicting methods that can be used for evaporators with R32.

HFO1234ze(E) vaporisation inside a Brazed Plate Heat Exchanger (BPHE): Comparison with HFC134a and HFO1234yf

This paper investigates the effects of heat flux, saturation temperature, and outlet conditions on HFO1234ze(E) boiling inside a Brazed Plate Heat Exchanger (BPHE). The effect of the heat flux on the heat transfer coefficients was remarkable. Similar consideration applies for outlet condition effects whereas the impact of saturation temperature was found to be lower. The frictional pressure drop shows a linear dependence on the refrigerant kinetic energy per unit volume. The two-phase flow boiling heat transfer coefficients were compared with a new model for refrigerant boiling inside BPHE (Longo et al., 2015): the mean absolute percentage deviation between calculated and experimental data is 7.2%. The present data points were compared with those of HFC134a and HFO1234yf previously measured inside the same BPHE under the same operating conditions: HFO1234ze(E) exhibits heat transfer coefficients very similar to HFC134a and HFO1234yf and frictional pressure drops slightly higher than HFC134a and HFO1234yf.

Performance of a Plate Heat Exchanger Operated with Water-Al<sub>2</sub>O<sub>3</sub> Nanofluid

This study is focused on experimental investigation of a selected type of brazed plate heat exchanger (PHEx). The main aim of the paper was to experimentally check the ability of nanofluids to enhance the performance of PHEx. A typical water-Al2O3 nanofluid was tested and compared to that of the base fluid, i.e. water. Nanoparticles were tested at the concentration of 0.1% and 1% by weight. Impact of the 1 day and 3 days break of operation of the tested PHEx on its performance was of particular interest. Pressure drop in all runs was measured as well. The Wilson approach was applied in order to estimate heat transfer coefficients for the PHEx passages. It was observed, that addition of nanoparticles resulted in deterioration of an overall heat transfer coefficient for the selected PHEx and tested conditions, i.e. temperature range and Reynolds number. Moreover, substantial increase of pressure drop was recorded after each break of operation of the tested PHEx.

Analysis of enhanced vapor desuperheating during condensation inside a plate heat exchanger

The presence of superheated vapor in condenser heat exchanger is common in many applications, as heat pump or organic Rankine cycle. Rarely taken into consideration in the literature of plate heat exchangers, the present article focuses on the influence of the superheated vapor on the condensation characteristics of an organic fluid (pentane) in a brazed plate heat exchanger (BPHE). A specific experimental approach has been developed for this objective. The tested BPHE prototype consists of 2 channels with chevron angle of 55°, and a hydraulic diameter equal to 4.4 mm. The effect of the pentane mass flux, 9–30 kg m−2 s−1, and the vapor superheat, 5–25 K, at a mean constant saturation temperature of 36.5 °C (1.029 bars), on the global and local thermo-hydraulic characteristics has been identified. An infrared (IR) metrology is used to distinguish the different fluid state distributions, which are representative of various heat transfers along the BPHE. The IR thermography shows a significant impact of the vapor superheat, on the fluid distribution at the channel inlet depending on the mass flux.Comparing the results with vapor superheat going from 5 to 25 K, we note: 1/an increase of the heat transfer coefficient reaching 70% for the lowest mass flux; 2/an increase of the pressure drop, whose rate (18%) is equivalent to the increase of the heat transfer coefficient for the larger mass fluxes. Superheated vapor is therefore very favorable to heat transfer for condensation in the gravity mode compared to the convective one. Based on experimental measurements and observations, various vapor desuperheating scenarios are tested. The analysis justifies that the suitable desuperheating scenario involves condensation from superheated vapor directly from the channel inlet with liquid vaporization from the condensate film.

Boiling of Binary Zeotropic Blends in the Plate Heat Exchanger of the Heat Pump

In this paper, we consider the process of boiling in the evaporator of the heat pump. Zeotropic binary refrigerants R32/R152a (30/70%) and R32/R134a (30/70%) are used as working medium. Calculations are made for brazed plate heat exchanger during boiling of zeotropic blend refrigerants with account of peculiarities of this process. Results of calculation of the heat transfer coefficient for zeotropic blends are given.

Experimental investigation on heat transfer characteristics and pressure drop of BPHE (brazed plate heat exchanger) using TiO2–water nanofluid

In this research, the effect of using TiO2–water nanofluid on heat transfer enhancement and pressure drop in a Brazed Plate Heat Exchanger used in domestic hot water system is investigated experimentally. TiO2 nanoparticles with 20nm diameter and 99+% purity are used for making the nanofluid at 0.3%, 0.8% and 1.5% weight concentration of suspended nanoparticles, in such experiments. This study is done on the brazed plate heat exchanger under turbulent flow condition. The effects of Reynolds number and weight concentration of nanoparticles on the heat transfer characteristics are investigated experimentally. This results in a significant increase in convective heat transfer coefficient through adding nanoparticles to distilled water. The results show that, the convective heat transfer coefficient and the overall heat transfer coefficient of TiO2–water nanofluid is increased with enhancement of Reynolds number and at a specified Reynolds number, heat transfer characteristics is enhanced by increasing weight concentration of nanoparticles in brazed plate heat exchanger. The maximum enhancement of the nanofluid convective heat transfer coefficient at 0.3%, 0.8% and 1.5% weight fraction of nanoparticles are about 6.6%, 13.5% and 23.7% respectively. Also the maximum enhancement of the nanofluid overall heat transfer coefficient at mentioned weight concentrations of nanoparticles are about 2.2%, 4.6% and 8.5% respectively. Finally, the nanofluid pressure drop at various levels of nanoparticles is measured experimentally. According to these results, increment in system pressure drop is negligible compared to the heat transfer improvement.

Thermal performance of brazed plate heat exchangers for a mixed-refrigerant Joule–Thomson cooler

The objective of the present work is to contribute to the development of a brazed plate heat exchanger as the recuperative heat exchanger for a mixed refrigerant Joule–Thomson cooler. In this study, the thermal performance of the recuperative heat exchanger is experimentally investigated. For the recuperative heat exchanger, the overall heat transfer coefficient varies from 38.3 to 362.5 W m−2 K−1 and the exergy efficiency is in the range of 54.2–85.7%. Moreover, four condensation correlations and ten evaporation correlations were utilized to assess the mixture's two-phase overall heat transfer coefficient, with the modification of the mixture's mass transfer resistance. The experimental data are well-predicted by two correlation combinations with mean absolute errors of 17.1% and 15.8%, respectively. Hence, these two correlation combinations are recommended for use. Finally, the thermal resistances of the mixture's two-phase transfer process are evaluated by the correlation combination, that best predicts the experimental data.

Numerical Investigation of a Chevron Type Brazed Plate Heat Exchanger

A numerical investigation has been carried out in the present work to study flow characteristics and thermal performance of a chevron type brazed plate heat exchanger (PHE). A local element-by-element analysis utilizing e-NTU method is employed for simulating the heat exchanger. In this approach, Nusselt number is expressed in terms of friction factor which in turn, is given as a function of chevron angle of the heat exchanger. Water has been used as cold and hot fluid. Effect of fluid flow rate and inlet temperatures on the heat duty, overall heat transfer coefficient, fluid outlet temperatures and pressure drop have been studied. When compared with literature results of intermating plate heat exchangers, chevron type plate heat exchanger gives greater heat transfer enhancement, though with increased pressure drop.

Impact of two-phase distribution systems on the performance of a microchannel evaporator

The design and the performance of an innovative shell-and-tube evaporator using round copper microchannels are presented in this article. This prototype has been designed aiming at the minimization of the refrigerant charge, which can be required by safety or environmental restrictions. Experimental data of heat transfer and pressure drop are reported in the present article. The measurements have been obtained with two different evaporator inlet headers and two different working fluids (i.e., R22 and R410A) to investigate the mutual influence of the design of the distribution system and the refrigerant properties on possible maldistribution issues. A computational procedure implementing different correlations has also been developed and validated against experimental data; this procedure allows the prediction of the performance of the same evaporator with a hydrocarbon, such as propane, and comparison of the prototype to a brazed-plate heat exchanger.