https://orcid.org/0000-0002-2218-4176
![Sample our Built Environment journals, sign in here to start your access, Latest two full volumes FREE to you for 14 days]({"type":"image" , "src" : "/sda/5926/TOC-Subject-Sample-2021-Built-Environment.jpg"})
ABSTRACT
Besides waste gas and liquid, high-temperature particles are important media of waste heat and their temperature exceeds 1000°C on many occasions. The cross-flow heat transfer is important in this waste heat recovering process, but there are few references reported about the theoretical modeling. Therefore, a theoretical model was developed for the cooling process in a horizontal moving bed of high-temperature particles. The purpose of the study is to estimate the influence of temperature field and flow field on heat transfer and bed resistance in the cross-flow cooling process. Three modes such as conduction, convection and radiation are considered in the model. This model was used to analyze heat transfer in a horizontal moving bed of cement clinker and was verified by comparing some simulative results with the tested and collected data from an actual cement clinker plant in China. The simulative temperature of cement clinker was 200°C as same as that collected in the actual cement clinker plant. In the moving bed, the highest pressure drop occurs at the front top and the strongest heat transfer occurs at the front bottom. In the considered conditions with even distribution of cooling air, the highest pressure drop is 3205.9 Pa/m, the biggest specific heat transfer rate of 1683.1 kW/m3. Thermal radiation plays a minor role in this cooling process with the biggest radiation proportion is only 0.149 at the front top. This mode plays a minor role in this cooling process of the cement clinker, comparing with the thermal convection. With constant flow rate of cooling air, the distribution can regulate the local cooling rate rather than the final temperature of the cement clinker.
Nomenclature
| A | = | area (m2) |
| As | = | specific surface area (m2) |
| c | = | specific heat capacity (J/(kg·°C)) |
| C | = | coefficient |
| d | = | diameter of particle (m) |
| e | = | porosity |
| E | = | emissive power (W/m2) |
| g | = | number |
| h | = | convective heat transfer coefficient (W/(m2·°C)) |
| H | = | height (m) |
| i, j | = | number |
| k | = | heat transfer coefficient (W/(m2·°C)) |
| l | = | interval number of particle size distribution |
| L | = | length (m) |
| m | = | division number of a single particle |
| n | = | number of micro units |
| Nu | = | Nusselt number |
| p | = | pressure (Pa) |
| Pr | = | Prandtl number |
| q | = | heat flux (W/m2) |
| Q | = | heat transfer rate (W) |
| r | = | radius of particle (m) |
| R | = | thermal resistance (m2·°C/W) |
| Re | = | Reynolds number |
| s | = | length of radiation path (m) |
| t | = | temperature (°C) |
| T | = | temperature (K) |
| u | = | velocity (m/s) |
| V | = | volume (m3) |
| w | = | weight percentage |
| W | = | width (m) |
| V | = | volume flow rate (m3/h) |
| Abbreviation | = | |
| LMTD | = | Logarithmic Mean Temperature Difference |
| CDQ | = | Coke Dry Quenching |
| Greek symbols | = | |
| α | = | absorptivity |
| ε | = | emissivity |
| η | = | efficiency |
| λ | = | thermal conductivity (W/(m·K)) |
| μ | = | dynamic viscosity (Pa·s) |
| ρ | = | density (kg/m3) |
| τ | = | temperature |
| ϕ | = | sphericity |
Acknowledgements
Project 2016YFB0601501 sported by National Key R&D Program of China is gratefully acknowledged.
Disclosure statement
No potential conflict of interest was reported by the author(s).
Additional information
Funding
Notes on contributors
Lisheng Pan
Lisheng Pan is an associate professor of Institute of Mechanics, Chinese Academy of Sciences. He received his M.S. degree and Ph.D. degree from Tianjin University in engineering thermal physics. His areas of interests are thermodynamics, refrigeration, heat pump, energy storage and waste heat recovery.
Weixiu Shi
Weixiu Shi is an associate professor of Beijing University of Civil Engineering and Architecture. She received her M.S. degree and Ph.D. degree from Tianjin University.
Xiaolin Wei
Xiaolin Wei is a professor of Institute of Mechanics, Chinese Academy of Sciences. He received his B.S. degree, M.S. degree and Ph.D. degree from Xi’an Jiaotong University.