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In the present study, a small brazed and commercial plate heat exchanger (PHE) with chevron angle 60° and symmetrical layout, was experimentally investigated. New correlations for calculating heat transfer and friction coefficients of hot flow channels were presented. Few studies have been done on the small PHEs and due to the industrial needs, it...
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Citations
... Staggered sheet layout was found to be highly productive than in-line layout for all geometrical parameters. Mohebbi et al. [38] performed experimental analysis on the heat transfer along with friction coefficients of the compact exchanger. In the study, a compact equipment with brazed and commercial plate with inclination angle 60° and even layout was experimentally examined. ...
Heat exchanger plays a crucial role in the functioning of chemical industries, diary and food processing industries, and thermal plants. The enhancements in heat exchangers are mainly aimed at minimizing the energy consumption. An efficient heat exchanger is one that provides high heat transfer rate with minimum pumping power at low cost for energy saving. PHEs are used in various engineering fields due to their simplicity, flexibility, and maintainability related to others. In this paper, passive surface enhancement methods for single-phase and two-phase flow and application of nanofluids in different types of PHE are reviewed. The effect of geometrical parameters on hydraulic-thermal performance and occurrence of fouling deposits in PHE are also discussed. The chevron angle is found to be the most dominating geometrical parameter to change the flow properties. HTC, Nu, and ΔP increased with the increase in β, γ, and ϕ. For the two-phase flow, ΔP increased with the rise in vapor quality, mass flow rate and reduced with increase in saturation pressure. The optimum geometrical parameters for maximum heat transfer are β: 30°-60°, γ: 0.075–0.6, and φ: 1.18–1.3. The use of nanofluids in laminar flow condition is suggested by most of the literature.
... Mohebbi and Veysi [18] investigated a small, brazed plate heat exchanger's thermohydraulic characteristics. The chevron angles were 60 • , and the modified Wilson plot was incurred to calculate the Nusselt numbers. ...
The present study focuses on the optimum design effectiveness in heat removal for small surfaces. Pin-fin made of solid and porous cylindrical shape forming chevron is investigated numerically using the finite element method. The design consists of 3-chevron and 5-chevron configurations connected to a heated block with fluid circulating between the chevron and above them. Variable Reynolds number and pin-fins height ranging from 2 mm to 8 mm are investigated. The full Navier–Stokes equation combined with the energy equation was solved in the presence of the solid pin-fins. The Darcy–Brinkman model with the effective energy equation is used in the presence of the porous pin-fins. The system is solved for Reynolds numbers ranging from 50 to 1000, thus remaining in the laminar regime. Results revealed that the best performance evaluation criterion is higher for the 8 mm porous pin-fins regardless of their permeability. If one ignores the pressure drop and friction contribution, a solid pin-fin having a height of 4 mm showed the best heat absorption mechanism.
... They incorporated all correlations for all β's into one correlation for Nu and another one for f. Similar studies have been carried out to further investigate the effect of different β's on heat transfer characteristics for single-phase heat transfer [7][8][9][10][11][12][13][14][15]. Heat transfer characteristics of nine CPHEs with different dimensions have been experimentally investigated by Yang et al. [16]. ...
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.
... As passive devices are easily installed and no external energy supply is required, these have been commonly implemented as alternative to active devices [66]. Examples of passive methods are rough surfaces [67,68]; artificial roughnessribs [69,70], corrugated surfaces [9,71,72], longitudinal fins [73]; extended surfacesbaffles [59,74,75]; swirl flow devices [76,77]; coiled tubes [78][79][80]; and flow additives as nanofluids (NF). NFs are produced by the addition of suspended nanoparticles (e.g. ...
Biofouling is the unwanted accumulation of deposits on surfaces, composed by organic and inorganic particles and (micro)organisms. Its occurrence in industrial equipment is responsible for several drawbacks related to operation and maintenance costs, reduction of process safety and product quality, and putative outbreaks of pathogens. The understanding on the role of operating conditions in biofouling development highlights the hydrodynamic conditions as key parameter. In general, (bio)fouling occurs in a higher extension when laminar flow conditions are used. However, the characteristics and resilience of biofouling are highly dependent on the hydrodynamic conditions under which it is developed, with turbulent conditions being associated to recalcitrant biodeposits. In industrial settings like heat exchangers, fluid distribution networks and stirred tanks, hydrodynamics play a dual function, affecting the process effectiveness while favouring biofouling formation. This review summarizes the hydrodynamics played in conventional industrial settings and provides an overview on the relevance of hydrodynamic conditions in biofouling development as well as in the effectiveness of industrial processes.
Phương pháp giản đồ Wilson là một phương pháp được sử dụng để xác định hệ số trao đổi nhiệt đối lưu trong một số quá trình truyền nhiệt. Đây là phương pháp được ứng dụng nhiều trong nghiên cứu thiết bị trao đổi nhiệt, đặc biệt đối với các thiết bị có bề mặt trao đổi nhiệt phức tạp, khó tiếp cận trong việc tính toán quá trình truyền nhiệt. Trong nghiên cứu này trình bày ứng dụng phương pháp giản đồ Wilson để phát triển phương trình số Nusselt của dòng lưu chất từ kết quả mô phỏng CFD. Một mô hình đường ống gia nhiệt cho nước với mặt trong ống có cánh dạng tròn, bên ngoài ống được cấp một dòng nhiệt không đổi đã được xem xét. Các mô hình toán học liên quan đến phương trình năng lượng, hồi quy tuyến tính được phân tích bằng phần mềm EES (Engineering Equation Solver). Kết quả nghiên cứu cho thấy, từ dữ liệu mô phỏng CFD bằng phương pháp giản đồ Wilson đã phát triển được phương trình số Nusselt của dòng nước với tương quan R2=0,9992. Qua đó cho thấy, phương pháp giản đồ Wilson có thể sử dụng vào trong nghiên cứu thiết bị trao đổi nhiệt không chỉ trong thực nghiệm mà còn có thể vận dụng vào trong nghiên cứu mô phỏng. Phương pháp này có thể vận dụng vào trong giảng dạy thí nghiệm hoặc mô phỏng số liên quan đến thiết bị trao đổi nhiệt cho sinh viên đại học.
In the present study, the numerical investigation of single-phase and steady-state water flow in a small-sized plate heat exchanger with a chevron type corrugation pattern, is performed in three-dimensional. For validating the numerical modeling, an empirical model of a commercial PHE is designed and a good agreement between the results of experimental tests and numerical modeling is obtained. Moreover, the influence of flow regime (150<Re<550), as well as geometrical parameters of chevron angle (β), corrugation depth (b), and corrugation pitch (λ) on the performance of the PHE are evaluated. In all corrugation depths and corrugation pitches, the maximum Nu-number and friction coefficient occur at β=60° and β=30°, respectively. Considering the simultaneous effect of heat transfer and friction, the JF factor is defined. The reducing trends of heat transfer and the increasing trends of friction are inferred by decreasing Re-number; however, the JF factor is increased. Besides, β=60° is the most favorable case from the performance point of view due to the formation of different flows. In this case, the JF factor increases compared to the other chevron angles. On the other hand, the increasing behavior of this factor is observed with increasing corrugation depth (b), which is 55% at β=60° and λ=8.3 mm compared to the commercial PHE. The decrease in the corrugation pitch (λ) also has a similar effect on the JF factor and increases it by 40% at β=60° and b= 2.3 mm compared to the commercial PHE. In general, it is inferred that the superior performance of the small-sized PHEs is associated with the decreased mass flow rate, the chevron angle of 60°, and the increased bλ ratio. By increasing the corrugation depth or decrementing the corrugation pitch, the weight and volume of the PHE showed an enhancement. In small PHEs, however, this weight and volume gain versus performance improvement can be ignored. It is recommended to reduce the corrugation pitch rather than increasing its depth as a decline in corrugation pitch does not enhance the volume of the small PHE.
Much of the present and future technology will be based on electronic devices that are operated using an electronic clip. Due to the continuous operation of the majority of electronic devices, the efficiency of such devices decreases because of inefficient cooling techniques. Therefore, the present study experimentally and numerically investigates the thermal resistance and friction factor for the flat plate heat exchanger in the range of Reynolds number 7500–38,000. The study also examines the effect of the number of passes on the thermal performance of a flat plate heat exchanger. Based on the experimental and numerical results of a 4-pass flat plate heat exchanger, the empirical correlation for the thermal resistance and friction factor is suggested to be within the error range of ± 3.5% and ± 5%, respectively. For the optimum performance of the flat plate heat exchanger, the thermal resistance and friction factor should be as low as possible. The numerical results show that the thermal resistance decreases, and the friction factor increases with the number of passes in the flat plate heat exchanger; therefore, out of 2, 4, and 6 passes, the study suggests that 4 passes provide a compromising option for thermal resistance as well as the friction factor.
