Techno-economic analysis of nitrogen-doped graphene/water nanofluid in various heat exchangers (A unified analysis)

Author(s):  
Yousif M Alkhulaifi ◽  
Shahzada Zaman Shuja ◽  
Bekir Sami Yilbas

Nitrogen-doped graphene (NDG)/water nanofluid is one of the emerging working fluids toward achieving high heating rates in heat transfer devices. In the present study, thermal performance improvement and techno-economic analysis of a double pipe, shell and tube, and plate heat exchangers are presented while incorporating NDG/water nanofluid as a working fluid. The variable properties of NDG nanofluid are incorporated and the influence of nanoparticle concentrations and mass flow rates on the device thermal performance and related costs are evaluated. The findings demonstrate that device heat transfer area and costs are adversely affected by using NDG/water nanofluid in all types of heat exchanging devices considered. An increase in heat transfer area is associated with the decrease of the specific heat capacity of the working fluid. The increase of heat transfer area can be as high as 58.5%, 45.1%, and 67.0% for double pipe, shell and tube, and plate heat exchangers, respectively. In addition, area increase becomes persistent with other types of nanoparticles used in the carrier fluid.

Energies ◽  
2020 ◽  
Vol 13 (11) ◽  
pp. 2737
Author(s):  
Francesca Ceglia ◽  
Adriano Macaluso ◽  
Elisa Marrasso ◽  
Maurizio Sasso ◽  
Laura Vanoli

Improvements in using geothermal sources can be attained through the installation of power plants taking advantage of low and medium enthalpy available in poorly exploited geothermal sites. Geothermal fluids at medium and low temperature could be considered to feed binary cycle power plants using organic fluids for electricity “production” or in cogeneration configuration. The improvement in the use of geothermal aquifers at low-medium enthalpy in small deep sites favours the reduction of drilling well costs, and in addition, it allows the exploitation of local resources in the energy districts. The heat exchanger evaporator enables the thermal heat exchange between the working fluid (which is commonly an organic fluid for an Organic Rankine Cycle) and the geothermal fluid (supplied by the aquifer). Thus, it has to be realised taking into account the thermodynamic proprieties and chemical composition of the geothermal field. The geothermal fluid is typically very aggressive, and it leads to the corrosion of steel traditionally used in the heat exchangers. This paper analyses the possibility of using plastic material in the constructions of the evaporator installed in an Organic Rankine Cycle plant in order to overcome the problems of corrosion and the increase of heat exchanger thermal resistance due to the fouling effect. A comparison among heat exchangers made of commonly used materials, such as carbon, steel, and titanium, with alternative polymeric materials has been carried out. This analysis has been built in a mathematical approach using the correlation referred to in the literature about heat transfer in single-phase and two-phase fluids in a tube and/or in the shell side. The outcomes provide the heat transfer area for the shell and tube heat exchanger with a fixed thermal power size. The results have demonstrated that the plastic evaporator shows an increase of 47.0% of the heat transfer area but an economic installation cost saving of 48.0% over the titanium evaporator.


Author(s):  
Shamkuwar S.C ◽  
◽  
Nitin Chopra ◽  
Mihir Kulkarni ◽  
Nikhil Ahire ◽  
...  

The main objective of the paper is to compare the performance of Shell and tube heat exchanger (STHE) and Plate heat exchanger (PHE) used in chillers. The paper deals with experimental investigation and comparison, which is based on actual testing of STHE and PHE. Both heat exchangers were designed and tested for a heat load of 6000 kcal/hr. In both types of heat exchangers, the primary working fluid used is Refrigerant R22 and secondary working fluid used is water. Theoretical analysis shows that PHE has a 9.67 % less heat transfer area than STHE. Experimental results show that overall heat transfer coefficient (OHTC) for PHE is higher than STHE by 30.96%. The paper also includes a comparison of the heat transfer rate (Q) of the two heat exchangers experimentally.


Author(s):  
Ece Özkaya ◽  
Selin Aradag ◽  
Sadik Kakac

In this study, three-dimensional computational fluid dynamics (CFD) analyses are performed to assess the thermal-hydraulic characteristics of a commercial Gasketed Plate Heat Exchangers (GPHEx) with 30 degrees of chevron angle (Plate1). The results of CFD analyses are compared with a computer program (ETU HEX) previously developed based on experimental results. Heat transfer plate is scanned using photogrammetric scan method to model GPHEx. CFD model is created as two separate flow zones, one for each of hot and cold domains with a virtual plate. Mass flow inlet and pressure outlet boundary conditions are applied. The working fluid is water. Temperature and pressure distributions are obtained for a Reynolds number range of 700–3400 and total temperature difference and pressure drop values are compared with ETU HEX. A new plate (Plate2) with corrugation pattern using smaller amplitude is designed and analyzed. The thermal properties are in good agreement with experimental data for the commercial plate. For the new plate, the decrease of the amplitude leads to a smaller enlargement factor which causes a low heat transfer rate while the pressure drop remains almost constant.


2017 ◽  
Vol 71 (5) ◽  
pp. 439-449
Author(s):  
Nikola Zlatkovic ◽  
Divna Majstorovic ◽  
Mirjana Kijevcanin ◽  
Emila Zivkovic

Plate heat exchanger is a type of heat exchanger that uses corrugated metal plates to transfer heat between two fluids. The plate corrugations are designed to achieve turbulence across the entire heat transfer area thus producing the highest possible heat transfer coefficients while allowing close temperature approaches. Subsequently, this leads to a smaller heat transfer area, smaller units and in some cases, fewer heat exchangers. In this work, an application for thermal and hydraulic computations of plate heat exchangers had been developed using Sharp Develop, an open source programming platform. During the development process, several literature methods and correlations for calculation of heat transfer coefficient and pressure drop in a plate heat exchanger have been tested and the selected four methods: Martin, VDI, Kumar and Coulson and Richardson have been incorporated into the software. The structure of the software is visually presented through several windows: a window for inserting input data, windows for showing the results of computation by each of the methods, a window for showing comparative analysis of the most important computation results obtained by all of the used methods and a help window for demonstrating the working principle of plate heat exchanger.


2020 ◽  
Vol 24 (1 Part A) ◽  
pp. 355-365
Author(s):  
Koray Karabulut

Plate heat exchangers have a widespread usage and the simplest parallel plate channel structures. Cross-corrugated ducts are basic channel geometries used in the plate heat exchangers. In this study, the increasing of heat transfer from the cross-corrugated triangular ducts by inserting triangular baffles with different placement angles into the channel upper side and pressure drop have been numerically investigated. Numerical calculations have been carried out to solve Navier-Stokes and energy equations by employing k-? turbulence model as 3-D and steady with ANSYS-FLUENT program. While inlet temperature of the air used as working fluid is 293 K, constant surface temperature values of the the lower corrugated channel walls are 373 K. The height of the baffle and apex angle of the corrugated duct have been taken constant as 0.5 H and 60?, respectively. Investigated Reynolds number range is 1000-6000 while the baffle placement angles are 30?, 45?, 60?, and 90?. Numerical results of this study are within 3.53% deviation with experimental study existed in literature. The obtained results have been presented as mean Nusselt number temperature and pressure variations of the fluid for each baffle angle. The temperature and velocity vector contour distributions have been also assessed for different Reynolds numbers and baffle angles. The value of the Num for the corrugated channel with 60? baffle angle is 8.2% higher than that of the 90? for the Re = 4000. Besides, for Re = 1000 the value of the pressure drop is 39% lower in the channel with 60? baffle angle than that of 90?.


Author(s):  
Ataollah Khanlari ◽  
Adnan Sözen ◽  
Halil İbrahim Variyenli

PurposeThe plate heat exchangers (PHE) with small size but large efficiency are compact types of heat exchangers formed by corrugated thin pressed plates, operating at higher pressures when compared to most other traditional exchangers. This paper aims to analyze heat transfer characteristics in the PHE experimentally and numerically.Design/methodology/approachComputational fluid dynamics analysis has been used to simulate the problem by using the ANSYS fluent 16 software. Also, the effect of using TiO2/water nanofluid as working fluid was investigated. TiO2/water nanofluid had 2% (Wt/Wt) nanoparticle content. To improve solubility of the TiO2nanoparticles, Triton X-100 was added to the mixture. The results have been achieved in different working condition with changes in fluid flow rate and its temperature.FindingsThe obtained results showed that using TiO2/water nanofluid improved the overall heat transfer coefficient averagely as 6%, whereas maximum improvement in overall heat transfer coefficient was 10%. Also, theoretical and experimental results are in line with each other.Originality/valueThe most important feature which separates the present study from the literature is that nanofluid is prepared by using TiO2nanoparticles in optimum size and mixing ratio with surfactant usage to prevent sedimentation and flocculation problems. This process also prevents particle accumulation that may occur inside the PHE. The main aim of the present study is to predict heat transfer characteristics of nanofluids in a plate heat exchanger. Therefore, it will be possible to analyze thermal performance of the nanofluids without any experiment.


Energies ◽  
2020 ◽  
Vol 13 (20) ◽  
pp. 5304
Author(s):  
Howard Lee ◽  
Ali Sadeghianjahromi ◽  
Po-Lun Kuo ◽  
Chi-Chuan Wang

An experimental study regarding the thermofluid characteristics of a shell-and-plate heat exchanger with different chevron angles (45°/45°, 45°/65°, and 65°/65°) with a plate diameter of 440 mm was carried out. Water was used as the working fluid on both sides and the corresponding temperatures ranged from 30–70 °C. The flow rate on the plate or shell side ranged from 10–60 m3/h. The effects of chevron angles on the heat transfer and fluid flow characteristics of shell-and-plate heat exchangers were studied in detail. With regard to the heat transfer performance on the plate side, a higher chevron angle (65°/65°) resulted in a significantly better performance than a low chevron angle (45°/45°). The effect of the chevron angle became even more pronounced at high Reynolds numbers. Unlike the plate side, an increase in the chevron angle had a negative effect on the heat transfer performance of the shell side. Additionally, this opposite effect was more prominent at low Reynolds numbers due to the comparatively large contribution of the manifold. The friction factor increased appreciably with the increase in the chevron angle. However, when changing the chevron angle from 45°/45° to 65°/65°, the increase in the friction factor was about 3–4 times on the plate side while it was about 2 times on the shell side. This can be attributed to the presence of the distribution/collection manifold on the shell side. Empirical correlations for the Nusselt number and friction factor were developed for different combinations of chevron angles with mean deviations of less than 1%.


2017 ◽  
Vol 67 (2) ◽  
pp. 13-24
Author(s):  
Štefan Gužela ◽  
František Dzianik ◽  
Martin Juriga ◽  
Juraj Kabát

AbstractNowadays, the operating nuclear reactors are able to utilise only 1 % of mined out uranium. An effective exploitation of uranium, even 60 %, is possible to achieve in so-called fast reactors. These reactors commercial operation is expected after the year 2035. Several design configurations of these reactors exist. Fast reactors rank among the so-called Generation IV reactors. Helium-cooled reactor, as a gas-cooled fast reactor, is one of them. Exchangers used to a heat transfer from a reactor active zone (i.e. heat exchangers) are an important part of fast reactors. This paper deals with the design calculation of U-tube heat exchanger (precisely 1-2 shell and tube heat exchanger with U-tubes): water – helium.


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