![Sample our Engineering & Technology journals, sign in here to start your access, latest two full volumes FREE to you for 14 days]({"type":"image" , "src" : "/sda/5933/TOC-Subject-Sample-2021-Engineering-Tech.jpg"})
ABSTRACT
This research investigates the use of metal foam inserts to enhance the thermal-hydraulic performance of double-tube heat exchangers, relevant for energy-efficient systems such as solar flat plate collectors. Motivated by the need for improved heat transfer efficiency, this study hypothesizes that metal foam integration can significantly boost performance. Through systematic experimental study, the impact of metal foam inserts on heat transfer and pressure drop characteristics is comprehensively evaluated across various configurations, spanning horizontal and vertical orientations. Experimental evaluations were conducted on four configurations, including both conventional and metal foam-integrated heat exchangers in horizontal and vertical orientations, using water as the working fluid and Nickel metal foam with 0.9 porosity and 10 PPI in the annular space. The findings highlight significant enhancements in heat transfer performance with metal foam integration across both horizontal and vertical heat exchanger configurations compared to conventional counterparts, particularly showcasing superior effectiveness and efficiency in the horizontal configuration. Results show that metal foam integration substantially enhances heat transfer, with horizontal configurations exhibiting a 14.56% higher heat transfer coefficient than vertical ones. Additionally, the comprehensive performance index improved by 1.17 times, indicating a better balance between heat transfer enhancement and pressure loss. These findings were validated against established correlations from the literature, confirming the superior effectiveness of horizontal metal foam heat exchangers.
Nomenclature
| L | = | Length of tube, m |
| d | = | Diameter-of-tube,m |
| DO | = | External diameter (m) |
| Di | = | Internal diameter(m) |
| Dh | = | Hydraulic diameter (m) |
| T | = | Temperature, oC |
| є | = | Effectiveness |
| Re | = | Reynolds number |
| Nu | = | Nusselt number |
| Pr | = | Prandtl number |
| Cp | = | Specific heat, kJ/kg-K |
| ∆p | = | pressure drop |
| ṁ | = | mass flow rate |
| P | = | Perimeter of the pipe (m) |
| U | = | Overall heat transfer coefficient w/m2K |
| P | = | Pressure, Pa |
| f | = | Friction factor |
| u | = | Velocity, m/s |
| PPI | = | Pores-per-inch or Pore-density |
| h | = | Heat transfer coefficient W/(m2.K) |
| Ƞ | = | Efficiency |
| dp | = | Pore diameter (m) |
| df | = | Fiber diameter (m) |
| Ni | = | Nickel |
| Greek Symbols | = | |
| ε | = | Porosity |
| λ | = | Thermal-conductivity, w/m-K |
| μf | = | Dynamic viscosity of the fluid |
| ν | = | Kinematic viscosity (m2/s) |
| pf | = | Fluid density (kg/m3) |
| Abbreviations | = | |
| DTHE | = | Double Tube Heat Exchanger |
| MFHX | = | Metal Foam Heat Exchanger |
| MF | = | Metal Foam |
| LMTD | = | Log Mean Temp Difference |
| HX | = | Heat Exchanger |
| HTC | = | Heat Transfer Coefficient |
| CPE | = | Comprehensive Performance Evaluation |
| Subscript | = | |
| eff | = | Effective |
Disclosure statement
No potential conflict of interest was reported by the author(s).