http://orcid.org/0000-0003-0525-8863
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ABSTRACT
Estimation of the cooling efficiency of an accelerated air for the needs of cooling of die forgings is presented. Temperature dependence of heat transfer coefficient (HTC) was calculated for different cooling conditions varied by airflow velocity, covering the range from 18 to 48 m/s. Time–temperature measurements performed on a full-scale semi-industrial cooling line provided similarity to conditions typical of industrial conveyor, which gives the results utilitarian significance in design of controlled processing (of steel forged products). Acquired HTC values, ranging from 164.7 to 298 W/m2 · K, were validated in numerical simulation of cooling complex-shape forgings and subject to experimental verification, indicating perfect agreement with physical measurements.
Nomenclature
| a | = | thermal diffusion coefficient |
| cp | = | specific heat |
| d | = | diameter of test probe |
| K | = | number of time steps |
| np. | = | number of grid space |
| R | = | radius of test probe |
| R2 | = | correlation coefficient |
| T | = | temperature |
| t | = | time |
| Tmeasured | = | measured temperature |
| Tp | = | surface temperature |
| v | = | cooling rate |
| Subscripts | = | |
| i | = | index of space point |
| Superscripts | = | |
| k | = | index of time point |
| Greek symbols | = | |
| α | = | heat transfer coefficient |
| β | = | non-negative coefficient |
| Δt | = | time interval |
| Δr | = | radius interval |
| λ | = | thermal conductivity |
| ρ | = | density |
Nomenclature
| a | = | thermal diffusion coefficient |
| cp | = | specific heat |
| d | = | diameter of test probe |
| K | = | number of time steps |
| np. | = | number of grid space |
| R | = | radius of test probe |
| R2 | = | correlation coefficient |
| T | = | temperature |
| t | = | time |
| Tmeasured | = | measured temperature |
| Tp | = | surface temperature |
| v | = | cooling rate |
| Subscripts | = | |
| i | = | index of space point |
| Superscripts | = | |
| k | = | index of time point |
| Greek symbols | = | |
| α | = | heat transfer coefficient |
| β | = | non-negative coefficient |
| Δt | = | time interval |
| Δr | = | radius interval |
| λ | = | thermal conductivity |
| ρ | = | density |
Acknowledgments
Special thanks are addressed to T. Skowronek, Ł. Lisiecki, and P. Micek.