•Recent studies conducted on use of nanofluids in heat exchangers are reviewed.•Fascinating aspects on combination of nanofluid with heat exchanger are presented.•Challenges and opportunities for ...future research are addressed and discussed.
Heat exchangers have already proven to be important devices for thermal systems in many industrial fields. In order to improve the efficacy of heat exchangers, nanofluids are recently employed as coolants in them. Regarding unique characteristics of nanofluids, research studies in this area have witnessed a remarkable growth. This paper reviews and summarizes recent investigations conducted on use of nanofluids in heat exchangers including those carried out on plate heat exchangers, double-pipe heat exchangers, shell and tube heat exchangers, and compact heat exchangers. Meanwhile, some fascinating aspects about combination of nanofluids with heat exchangers are introduced. In addition, the challenges and opportunities for future research are presented and discussed.
•A new metaheuristic based on the hunting behavior of falcons (FOA) is proposed.•FOA was applied efficiently in several benchmark functions for single-objective.•Total cost decreasing 28 and 57.8% ...for shell-and-tube heat exchanger cases using FOA.•EGU units reduced 15.42% for plate-fin heat exchanger case 1 using FOA.•Effectiveness increasing 10% for plate-fin heat exchanger case 2 using FOA.
This paper proposes a novel metaheuristic optimizer based on the hunt behavior of falcons called Falcon Optimization Algorithm (FOA). FOA is a robust and powerful stochastic population-based algorithm that needs the adjustment of few parameters for its three-stage movement decision. Simulation results based on well-known twelve benchmark single-objective functions demonstrate the efficiency, effectiveness and robustness of the proposed method in comparison to other algorithms. Furthermore, the results of its single-objective application in heat exchangers shell-and-tube and plate-fin types allowed better results than previous works for the objective functions total cost for shell-and-tube heat exchanger (28% and 57.8% of reduction for cases 1 and 2, respectively) and number of entropy generation units (15.42% of reduction for case 1) and effectiveness (10% of increasing for case 2) for plate-fin heat exchanger type, alongside with a thermal-hydraulic discussion. Moreover, the FOA reached some solutions better than those previously reported in the literature.
•Compact heat exchangers for S-CO2 power cycle application are introduced.•The heat transfer mechanisms and correlations are described and summarized.•Thermal hydraulic performances of respective ...compact heat exchangers are compared.
This paper first presents a review of compact heat exchanger technology for a supercritical carbon dioxide (S-CO2) power cycle application to provide holistic insights for designing a power system and selecting appropriate heat exchangers. This is because a compact heat exchanger plays a key role in the S-CO2 power system to have small footprint while maintaining structural integrity. The developments and characteristics of various compact heat exchangers are briefly described, and their heat transfer mechanisms and correlations obtained from open literatures are summarized, enabling the researchers to obtain information quickly for their needs. From the selected correlations, thermal hydraulic performances of compact heat exchangers are compared for the S-CO2 recuperator operating region.
•Designed, fabricated, and tested a flat plate manifold microchannel heat exchanger.•Developed a specially designed manifold to allow distribution of the flow.•Achieved heat transfer coefficients as ...high as 66,000 W/m2K for water.•Demonstrated reasonable agreement between the experimental and the numerical results.•Potential use is in process, air conditioning and refrigeration applications.
The design and performance testing of a single-phase, flat plate, manifold microchannel heat exchanger with water as the working fluid are discussed in this paper. The aim of this study was to explore the use of manifolding of microchannels for performance enhancement of plate heat exchangers for single-phase, low heat flux (process type) applications operating in a counter flow configuration. The paper discusses the design of the heat exchanger, followed by the experimental testing and numerical simulation results. The experimental tests reveal that the heat exchanger is capable of delivering an overall heat transfer coefficient of close to 20,000 W/m2K at flow rates as low as 20 g/s (corresponding to a microchannel Reynolds number of 30) and a pressure drop per length value of 5.85 bar/m. The experimental results also are compared with established counter flow heat exchanger ε-NTU correlations to verify counter flow performance. Further, numerical simulation results for a single unit cell of the same geometry, which show reasonable agreement with the experimental results, are also described in this paper. The current work demonstrates successful use of microgrooves/microchannels for performance enhancement of plate heat exchangers for diverse industrial applications, including the refrigeration/air conditioning, process, and power production sectors.
•A new semi-numerical method for the calculation of tube heat exchangers is presented.•An exact analytical model for a two-pass cross-current heat exchanger was developed.•A numerical model of a ...two-pass cross-current boiler steam superheater was built.•The fluid temperatures obtained by the exact and numerical model were compared.•The temperature-dependent specific heat capacities of the fluids were considered.
The paper presents a mathematical model of a steam reheater in a steam boiler installed in a power unit of 1000 MW. A new numerical-analytical method was used to determine the temperature distribution of steam, flue gas, and the reheater’s tube walls. The reheater is a two-pass cross-current heat exchanger. There are 44 panels of tubes on the width of the boiler. The steam flows parallel through 20 pipes in each pass. An analytical model of the superheater was developed with the assumption of the constant physical properties of steam and flue gas. The results of steam and flue gas temperature calculations obtained by the proposed method were compared with the exact method’s results. Very high accuracy of estimates was attained even if the whole superheater is divided into a few control volumes. The results of the first and second pass steam temperature calculations were compared using the P-NTU (Effectiveness - Number of Transfer Units) method. A perfect match between the steam temperature and the average temperature of the flue gas at the outlet of the reheater was found. The advantage of the developed method of superheaters modeling is the possibility to model heat exchangers with complex flow systems. The calculations were also carried out for temperature-dependent physical properties of steam and flue gas.
This paper presents a method for heat exchanger network (HEN) optimisation considering plate heat exchangers (PHEs), incorporating detailed PHEs design. The developed method starts from a ...mathematical model based on the Advanced Grid Diagram, which can optimise the HEN structure. The model minimises the energy consumption cost with the constraints that enable a solution thermodynamically feasible. Then comes the heat exchanger type selection part, which is provided by a graphical tool helping to identify which types of the heat exchanger are feasible. The feasible temperature range can be easily visualised to avoid the temperature violation of PHEs. This selection part integrates the area calculation and cost calculation with the detailed heat exchanger design. The method has been tested by a case study of crude oil distillation system illustrating that the application of brazed plate heat exchangers (BHEs) of CB series manufactured by Alfa Laval can save 6.6% of the investment cost for new heat exchangers compared with the retrofit plan that only shell-and-tube and double pipe heat exchangers are used.
•A framework for HEN optimisation and heat exchanger type selection.•A method for detailed plate heat exchanger design is proposed.•Advanced Grid Diagram-based method helps to avoid the temperature violation.•A case study to illustrate the proposed method.•The brazed plate heat exchanger of CB series has advantage on investment saving.
•A new channel geometry for printed circuit heat exchangers is proposed and optimized.•Provide thermal-hydraulic performance of the optimized channel geometry.•Hydraulic performance for the optimized ...geometry is up to 2.5 times better.•Overall performance of the optimized channel geometry is up to 16–21% higher.
This paper presents the thermo-hydraulic performance analysis of the printed circuit heat exchangers (PCHEs) with new channel geometries. A new channel geometry for the PCHEs) has been proposed based on a staggered arrangement of sinusoidal fins. Initially, thermal and hydraulic performance of the proposed channel geometry was computed numerically and was compared with the performance of the conventional zigzag channel geometry using supercritical carbon dioxide (sCO2) as a working fluid. Later, the suggested geometry was optimized using response surface methodology in combination with the genetic algorithm. Lastly, thermal and hydraulic performance of the optimized channel geometry was computed numerically along with the zigzag channel geometry for a wide range of Reynolds number based on which heat transfer and pressure drop correlations were proposed. Computed results show that hydraulic performance of the optimized proposed channel geometry is up to 2.5 times better in comparison with the conventional zigzag channel geometry with identical thermal characteristics. Moreover, the overall performance of the optimized proposed channel geometry was found up to 21% and 16% higher for the cold and hot side, respectively.
•Recent research of three kinds of surface heat exchangers are reviewed.•The STHXs with novel combined helical baffles have been reviewed.•The primary surface heat exchangers with compact surfaces ...have been reviewed.•The direct and indirect air-cooled heat exchangers have been reviewed.
In the present study, the recent research of three kinds of surface heat exchangers, i.e., shell-and-tube heat exchangers with helical baffles, air-cooled heat exchangers used in large air-cooled systems, and primary surface heat exchangers are reviewed. They are used in the energy conversion and utilization for liquid to liquid, gas to gas and liquid to gas heat exchange, respectively. It can be concluded that the helical baffled shell-and-tube heat exchangers (STHXs) should be used to replace the conventional segmental baffled STHXs in industries, despite there are a lot of research work have to be done, especially on the novel combined helical baffles. The primary surface gas to gas heat exchangers are developing towards to the more complex 3D CC primary surfaces, such as the double-wave CC primary surface, offset-bubble primary surface and 3D anti-phase secondary corrugation. The whole performance for the air-cooled heat exchangers in the air cooling system and the multi-objectives optimization for air-cooled heat exchangers should be paid more attention, considering the heat transfer, pumper power, space usage and other economic influence factors.
•Novel compact plate-fin heat exchangers fabricated by laser powder bed fusion (LPBF)•Experimental and numerical investigation of different plate-fin heat exchangers•Plate-fin heat exchanger with ...twisted fins exhibits superior thermal performance•Improved rectangular fins improve coefficient of performance and overall performance
Plate-fin heat exchanger (PFHX) is one of the vital compact heat exchangers due to its high heat transfer area per unit volume and promising potentials in industrial applications where dimensions and weight are limited. Additive manufacturing presents great potentials for fabricating novel compact heat exchangers. In this work, three types of compact heat exchangers including a PFHX with twisted fins, a PFHX with improved rectangular fins and a PFHX with conventional rectangular fins are manufactured using the laser powder bed fusion (LPBF) technology. The experimental tests together with numerical simulations are conducted to evaluate the thermal performance and pressure drop of the heat exchangers. The results show that PFHX with twisted fins exhibits superior thermal performance among the three heat exchangers, and the PFHX with improved rectangular fins has the highest experimental coefficient of performance (COP) and provides outstanding overall performance. Furthermore, the impact of LPBF accuracy on the performance of heat exchanger are discussed to provide guidance for future designs.
•Melting and solidification of PCM inserted by metallic foam was simulated in MTHX.•Inserting metallic foam and increasing inner tubes expedite phase change process.•Use of metallic foam in ...solidification is more efficient than in melting.•Changing the tube arrangement inside PCM composite is more efficient than in pure PCM.
In this paper, melting and solidification processes of phase change material embedded in metallic porous foam in a multi-tube heat exchanger are investigated numerically under local non-equilibrium thermal condition. RT 35 is used as phase change material in middle shell of 3D multi-tube heat exchanger. Also, water flows across inner tube/tubes and outer tube as a heat transfer fluid (HTF). The effects of number of inner tubes, their arrangement as well as porosity of metallic foam on thermal characteristics of heat storage unit are studied. Results show that increasing number of inner tubes and adding metallic foam enhance melting and solidification rates significantly. A composite of phase change material/metallic foam with porosity of ε=0.7 engenders shorter melting and solidification time comparing to pure PCM. Arrangement of inner tubes has no effect on melting rate of metal foam/PCM composite. By inserting metallic foam with porosities ε=0.9and ε=0.7, melting time is decreased by 14% and 55%, respectively. Highest melting rate is for case with four inner tubes for all porosities of metallic foam. Regarding solidification process in pure PCM, case with four tubes shows shorter solidification time. Also, highest solidification rate amid composites of phase change material/metallic foam is seen for case with three tubes. Consequently, inserting metallic foam is more efficient in solidification process rather than the melting one. Moreover, increasing number of inner tubes has more influence on phase change rates in metal foam/PCM composites compared to pure PCM.
