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ABSTRACT
The present work conducts an experimental investigation into the influence of flow, thermodynamic and geometrical characteristics of the wavy strip on exergy loss and dimensionless exergy loss in a tube in tube heat exchanger. The working fluid is water with hot water passing the inner tube and cold water passing annulus. Wavy strips with four different angles and three widths were investigated experimentally. The result of exergy loss and dimensionless exergy loss for various conditions is presented and on the basis of curve fitting, three empirical correlations are suggested to predict dimensionless exergy loss in a double tube heat exchanger.
Highlights
• Exergy analysis of a double tube heat exchanger with wavy strip inserts is studied.
• Dependence of exergy and dimensionless exergy losses on the width and the angel of wavy strip inserts are presented.
• Effect of flow and thermodynamic properties on exergy and dimensionless exergy losses are clarified.
• Exergy loss increases with the increase of wavy strip width and decrease of wavy strip angle.
• Exergy loss increases with the decrease of heat capacity ratio
Nomenclature
| cp,w | = | specific heat at constant pressure J/kg.K |
| Cmin | = | minimum heat capacity W/K |
| Cmax | = | maximum heat capacity W/K |
| Cr | = | heat capacity ratio (dimensionless) |
| E | = | exergy loss, W |
| e | = | dimensionless exergy loss |
| H | = | specific enthalpy j/kg |
| L | = | length of one wave, m |
| ṁ | = | mass flow rate, kg/s |
| Nu | = | Nusselt number |
| Pr | = | Prandtl number |
| Q | = | heat transfer rate, W |
| Qmax | = | maximum heat transfer, W |
| Re | = | Reynolds number |
| s | = | specific entropy, j/Kg.K |
| T | = | temperature, K |
| w | = | wavy strip width, m |
| Xp | = | predicted value |
| Xa | = | actual (experimental) data |
Greek letters
| ε | = | effectiveness (dimensionless) |
| θ | = | wavy strip angle, degree |
Subscripts
| c | = | cold |
| h | = | hot |
| i | = | inner |
| o | = | outer |
| in | = | inlet |
| out | = | outlet |
| e | = | environment condition |
| w | = | water |