scholarly journals Experimental Investigation and Comparison of the Thermal Performance of Additively and Conventionally Manufactured Heat Exchangers

Metals ◽  
2021 ◽  
Vol 11 (4) ◽  
pp. 574
Author(s):  
Ana Vafadar ◽  
Ferdinando Guzzomi ◽  
Kevin Hayward
Keyword(s):  
Surface Roughness ◽  
Thermal Performance ◽  
Heat Exchangers ◽  
High Efficiency ◽  
Cooling System ◽  
Fluid Dynamic ◽  
Dynamic Performance ◽  
Experimental Studies ◽  
Manufacturing Method ◽  
Industrial Sectors

Air heat exchangers (HXs) are applicable in many industrial sectors because they offer a simple, reliable, and cost-effective cooling system. Additive manufacturing (AM) systems have significant potential in the construction of high-efficiency, lightweight HXs; however, HXs still mainly rely on conventional manufacturing (CM) systems such as milling, and brazing. This is due to the fact that little is known regarding the effects of AM on the performance of AM fabricated HXs. In this research, three air HXs comprising of a single fin fabricated from stainless steel 316 L using AM and CM methods—i.e., the HXs were fabricated by both direct metal printing and milling. To evaluate the fabricated HXs, microstructure images of the HXs were investigated, and the surface roughness of the samples was measured. Furthermore, an experimental test rig was designed and manufactured to conduct the experimental studies, and the thermal performance was investigated using four characteristics: heat transfer coefficient, Nusselt number, thermal fluid dynamic performance, and friction factor. The results showed that the manufacturing method has a considerable effect on the HX thermal performance. Furthermore, the surface roughness and distribution, and quantity of internal voids, which might be created during and after the printing process, affect the performance of HXs.

Design Study of a Humidification Tower for the Advanced Humid Air Turbine System

2005 ◽  
Author(s):  
Hidefumi Araki ◽  
Shinichi Higuchi ◽  
Shinya Marushima ◽  
Shigeo Hatamiya
Keyword(s):  
Gas Turbine ◽  
Heat Exchangers ◽  
High Efficiency ◽  
Cooling System ◽  
Pressure Ratio ◽  
Humid Air ◽  
Air Turbine ◽  
Water Atomization ◽  
Air Cooler ◽  
Compressor Work

The AHAT (advanced humid air turbine) system, which can be equipped with a heavy-duty, single-shaft gas turbine, aims at high efficiency equal to that of the HAT system. Instead of an intercooler, a WAC (water atomization cooling) system is used to reduce compressor work. The characteristics of a humidification tower (a saturator), which is used as a humidifier for the AHAT system, were studied. The required packing height and the exit water temperature from the humidification tower were analyzed for five virtual gas turbine systems with different capacities (1MW, 3.2MW, 10MW, 32MW and 100MW) and pressure ratios (π = 8, 12, 16, 20 and 24). Thermal efficiency of the system was compared with that of a simple cycle and a recuperative cycle with and without the WAC system. When the packing height of the humidification tower was changed, the required size varied for the three heat exchangers around the humidification tower (a recuperator, an economizer and an air cooler). The packing height with which the sum total of the size of the packing and these heat exchangers became a minimum was 1m for the lowest pressure ratio case, and 6m for the highest pressure ratio case.

scholarly journals Experimental studies into the fluid dynamic performance of the coolant flow in the mixed core of the Temelin NPP VVER-1000 reactor

2015 ◽  
Vol 1 (3) ◽  
pp. 174-178
Author(s):  
S.M. Dmitriev ◽  
D.V. Doronkov ◽  
Ye.N. Polozkova ◽  
A.N. Pronin ◽  
V.D. Sorokin ◽  
...  
Keyword(s):  
Fluid Dynamic ◽  
Dynamic Performance ◽  
Experimental Studies ◽  
Coolant Flow

Thermal Performance of Multipass Parallel and Counter-Cross-Flow Heat Exchangers

2006 ◽  
Vol 129 (3) ◽  
pp. 282-290 ◽  
Author(s):  
Luben Cabezas-Gómez ◽  
Hélio Aparecido Navarro ◽  
José Maria Saiz-Jabardo
Keyword(s):  
Heat Exchanger ◽  
Thermal Performance ◽  
Heat Exchangers ◽  
Experimental Studies ◽  
Cross Flow ◽  
Numerical Procedure ◽  
Complex Flow ◽  
Flow Heat ◽  
Small Elements ◽  
Effectiveness Data

A thorough study of the thermal performance of multipass parallel cross-flow and counter-cross-flow heat exchangers has been carried out by applying a new numerical procedure. According to this procedure, the heat exchanger is discretized into small elements following the tube-side fluid circuits. Each element is itself a one-pass mixed-unmixed cross-flow heat exchanger. Simulated results have been validated through comparisons to results from analytical solutions for one- to four-pass, parallel cross-flow and counter-cross-flow arrangements. Very accurate results have been obtained over wide ranges of NTU (number of transfer units) and C* (heat capacity rate ratio) values. New effectiveness data for the aforementioned configurations and a higher number of tube passes is presented along with data for a complex flow configuration proposed elsewhere. The proposed procedure constitutes a useful research tool both for theoretical and experimental studies of cross-flow heat exchangers thermal performance.

scholarly journals A New Conformal Cooling System for Plastic Collimators Based on the Use of Complex Geometries and Optimization of Temperature Profiles

Polymers ◽  
2021 ◽  
Vol 13 (16) ◽  
pp. 2744
Author(s):  
Jorge Manuel Mercado-Colmenero ◽  
Abelardo Torres-Alba ◽  
Javier Catalan-Requena ◽  
Cristina Martin-Doñate
Keyword(s):  
Thermal Performance ◽  
Cycle Time ◽  
Cooling System ◽  
Plastic Material ◽  
Dynamic Performance ◽  
Conformal Cooling ◽  
Cooling Channels ◽  
Optical Part ◽  
Part Surface ◽  
Plastic Parts

The paper presents a new design of conformal cooling channels, for application in collimator-type optical plastic parts. The conformal channels that are presented exceed the thermal and dynamic performance of traditional and standard conformal channels, since they implement new sections of complex topology, capable of meeting the high geometric and functional specifications of the optical part, as well as the technological requirements of the additive manufacturing of the mold cavities. In order to evaluate the improvement and efficiency of the thermal performance of the solution presented, a transient numerical analysis of the cooling phase has been carried out, comparing the traditional cooling with the new geometry that is proposed. The evolution of the temperature profile versus the thickness of the part in the collimating core with greater thickness and temperature, has been evaluated in a transient mode. The analysis of the thermal profiles, the calculation of the integral mean ejection temperature at each time of the transient analysis, and the use of the Fourier formula, show great improvement in the cycle time in comparison with the traditional cooling. The application of the new conformal design reduces the manufacturing cycle time of the collimator part by 10 s, with this value being 13% of the total manufacturing cycle of the plastic part. As a further improvement, the use of the new cooling system reduces the amount of thickness in the collimator core, which is above the ejection temperature of the plastic material. The improvement in the thermal performance of the design of the parametric cooling channels that are presented not only has a significant reduction in the cycle time, but also improves the uniformity in the temperature map of the collimating part surface, the displacement field, and the stresses that are associated with the temperature gradient on the surface of the optical part.

scholarly journals Numerical Assessment of Earth to Air Heat Exchanger with Variable Humidity Conditions in Greenhouses

Energies ◽  
2021 ◽  
Vol 14 (5) ◽  
pp. 1368
Author(s):  
Di Qi ◽  
Chuangyao Zhao ◽  
Shixiong Li ◽  
Ran Chen ◽  
Angui Li
Keyword(s):  
Heat Exchanger ◽  
Relative Humidity ◽  
Thermal Performance ◽  
Heat Exchangers ◽  
Energy Savings ◽  
Volume Flow Rate ◽  
Fluid Dynamic ◽  
Small Diameter ◽  
The Earth ◽  
The Impact

Earth to air heat exchangers are widely utilized to cool or heat passive buildings for energy savings. They often need to deal with high humidity air conditions, especially in the greenhouse due to plant transpiration, and the condensation phenomenon is frequently observed during the cooling process. To evaluate the effect of humidity and condensation on thermal performance, a three dimensional computational fluid dynamic (3D-CFD) model was developed. The distribution of relative humidity in each pipe was investigated, and the impact of inlet air relative humidity on the integrated performance of the earth to air heat exchanger was discussed. The effects of inlet air temperature and volume flow rate were also analyzed. Moreover, the influence of the heat exchanger configurations on the performance of the air condensation was researched. The results indicated that condensation had few effects on the airflow distribution uniformity of the earth to air heat exchanger, while it acted observably on the thermal performance. In addition, humid air in a small diameter pipe tended to condense more easily. Humidity and condensation should be taken into consideration for the design of earth to air heat exchangers in greenhouses during engineering applications.

Technoeconomic Optimization of Turbocompression Cooling Systems

2017 ◽  
Author(s):  
Spencer C. Gibson ◽  
Derek Young ◽  
Todd M. Bandhauer
Keyword(s):  
Heat Exchangers ◽  
Power Plants ◽  
High Efficiency ◽  
Waste Heat ◽  
Cooling System ◽  
Payback Period ◽  
Low Grade ◽  
Air Cooling ◽  
Total System ◽  
Cooling Systems

Low grade waste heat streams with temperatures near 100°C are abundant, presenting a significant opportunity to reduce primary energy consumption across the world. For example, thermally activated cooling systems can utilize waste heat to meet air conditioning loads. Recently, a turbocompression cooling system (TCCS) that utilizes low grade waste heat from power plants was investigated to improve the economic viability of dry air cooling systems. The TCCS utilizes Rankine and vapor-compression cycles that are directly coupled through a high efficiency centrifugal turbine and a compressor. In this paper, a coupled thermodynamic, heat transfer, and economic model for a TCCS is applied to utilizing low grade engine coolant waste heat to meet cargo ship cooling load requirements while minimizing the payback period for a particular operational scenario. The results of this study show that with a constant heat input of 2 MW, the liquid coupled turbocompression cooling system provided 642 kW of cooling with a payback period of 2 years and 6 months, and the total cost of the heat exchangers made up more than 84% of the total system cost. In addition, a sensitivity analysis showed that the effectiveness of the power cycle heat exchangers have a stronger influence on the payback period than the cooling cycle heat exchangers.

Experimental Analysis to Optimize the Performance of Air Curtains and Heat Exchangers

2015 ◽  
pp. 590-640
Author(s):  
Samuel Mariano do Nascimento ◽  
Gustavo Galdi Heidinger ◽  
Pedro Dinis Gaspar ◽  
Pedro Dinho Silva
Keyword(s):  
Mathematical Model ◽  
Energy Consumption ◽  
Heat Exchanger ◽  
Thermal Performance ◽  
Environmental Conditions ◽  
Heat Exchangers ◽  
Heat Load ◽  
Experimental Studies ◽  
Air Curtain ◽  
Back Panel

This chapter reports an overview about experimental studies concerning the thermal performance of air curtains and heat exchangers installed in vertical open refrigerated display cases. The air curtain analysis shows the influence on the thermal performance by varying the width of the discharge air grille and the perforation density of the back panel by a mathematical model. The variation on the perforation density of the back panel and the width of discharge air grille alter significantly the thermal entrainment factor and the energy consumption of the equipment. Focusing the influence of environmental conditions on the performance of the heat exchanger, a second mathematical model was developed to evaluate the total heat load, its partial components and the condensate water mass. This analysis provides valuable information to the design of the air curtain and heat exchanger based on in-store environmental conditions and airflow efficiency.

Design Study of a Humidification Tower for the Advanced Humid Air Turbine System

2005 ◽  
Vol 128 (3) ◽  
pp. 543-550 ◽  
Author(s):  
Hidefumi Araki ◽  
Shinichi Higuchi ◽  
Shinya Marushima ◽  
Shigeo Hatamiya
Keyword(s):  
Gas Turbine ◽  
Heat Exchangers ◽  
High Efficiency ◽  
Cooling System ◽  
Pressure Ratio ◽  
Humid Air ◽  
Air Turbine ◽  
Water Atomization ◽  
Air Cooler ◽  
Compressor Work

The advanced humid air turbine (AHAT) system, which can be equipped with a heavy-duty, single-shaft gas turbine, aims at high efficiency equal to that of the HAT system. Instead of an intercooler, a WAC (water atomization cooling) system is used to reduce compressor work. The characteristics of a humidification tower (a saturator), which is used as a humidifier for the AHAT system, were studied. The required packing height and the exit water temperature from the humidification tower were analyzed for five virtual gas turbine systems with different capacities (1, 3.2, 10, 32, and 100MW) and pressure ratios (π=8, 12, 16, 20, and 24). Thermal efficiency of the system was compared with that of a simple cycle and a recuperative cycle with and without the WAC system. When the packing height of the humidification tower was changed, the required size varied for the three heat exchangers around the humidification tower (a recuperator, an economizer, and an air cooler). The packing height with which the sum total of the size of the packing and these heat exchangers became a minimum was 1m for the lowest pressure ratio case, and 6m for the highest pressure ratio case.

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