Li et al. (2025) Study on the Estimation of Greenhouse Sensible Heat Flux Based on the Surface Renewal Method: Validation and Calculation Results

Identification

• Journal: Agriculture
• Year: 2025
• Date: 2025-11-26
• Authors: Yang Li, Yongguang Hu, Yongzong Lu, Jizhang Wang
• DOI: 10.3390/agriculture15232439

Research Groups

• School of Agricultural Engineering, Jiangsu University, Zhenjiang 212013, China

Short Summary

This study evaluated the applicability of the surface renewal (SR) method for estimating sensible heat flux (H) in a Venlo-type greenhouse with tomato plants. It found that the Chen method, which incorporates friction velocity, significantly outperformed the traditional Snyder method under various weather and operating conditions, providing a reliable and accurate tool for greenhouse heat flux estimation.

Objective

• To explore the applicability and accuracy of the surface renewal (SR) method for estimating sensible heat flux (H) in semi-closed, actively heated Venlo-type greenhouses, specifically comparing the traditional Snyder method and the Chen method, to provide a reliable basis for deriving crop evapotranspiration (ETc) through the energy balance equation.

Study Configuration

• Spatial Scale: A Venlo-type greenhouse (length 35.2 m, width 25.2 m, eave height 6 m, gutter height 5.5 m) located in Dagang District, Zhenjiang City, Jiangsu Province, China (32.181441° N, 119.629464° E), at an altitude of 18.5 m. The study focused on tomato plants.
• Temporal Scale: The experiment was conducted from 20 November 2024 to 9 January 2025 (51 days). High-frequency temperature and wind speed data were sampled at 10 Hz, while other micrometeorological data were sampled at 1 min intervals.

Methodology and Data

• Models used:
  • Surface Renewal (SR) method (general theory)
  • Snyder method (traditional SR model)
  • Chen method (improved SR model, incorporating friction velocity, u*)
  • Energy Balance Model (R'n = H + LE + G) for deriving actual sensible heat flux (Ho).
  • Evaporimeter method for measuring latent heat flux (LE), with conversion using an evaporation coefficient (Kc = 1.7) for mature tomatoes.
• Data sources: Micrometeorological data collected using a surface renewal observation system, including:
  • CR1000X data logger
  • Air temperature and humidity sensor (SM6395B)
  • Net radiation sensor (JTBQ-2)
  • Wind speed sensor (W410C2)
  • High-frequency thermocouple (Type E)
  • Soil heat flux plate (SN-3001-TR-SHF-N01)
  • Evaporimeter (J16021)
  • Electronic balance (ST)
  • Artificial heating energy (Qh) calculated based on heating equipment rated power, thermal efficiency, and cumulative operating time.

Main Results

• Sensible Heat Flux (H) Dynamics: Greenhouse sensible heat flux reached a maximum of 45 W/m² during sunny daytime and a minimum of 5 W/m² at night, recovering to 10–20 W/m² during nighttime heating.
• Chen Method Superiority: The Chen method consistently demonstrated significantly higher accuracy and stability compared to the Snyder method across all tested conditions.
  • Sunny Daytime: Chen method: R² = 0.722, Pearson's r = 0.861, RMSE = 18.6 W/m², MAE = 14.3 W/m². Snyder method: R² = 0.543, Pearson's r = 0.693, RMSE = 27.9 W/m², MAE = 21.5 W/m².
  • Sunny Nighttime (with heating): Chen method: R² = 0.712, Pearson's r = 0.856, RMSE = 9.8 W/m², MAE = 7.6 W/m². Snyder method: R² = 0.525, Pearson's r = 0.656, RMSE = 16.4 W/m², MAE = 12.9 W/m².
  • Cloudy Daytime: Chen method: R² = 0.755, Pearson's r = 0.876, RMSE = 15.2 W/m², MAE = 11.8 W/m². Snyder method: R² = 0.615, Pearson's r = 0.765, RMSE = 22.7 W/m², MAE = 17.9 W/m².
  • Cloudy Nighttime (with heating): Chen method: R² = 0.754, Pearson's r = 0.815, RMSE = 8.3 W/m², MAE = 6.5 W/m². Snyder method: R² = 0.614, Pearson's r = 0.615, RMSE = 13.7 W/m², MAE = 10.8 W/m².
• Overall Performance (Entire Period): The Chen method achieved an overall R² of 0.733 and a Pearson's r of 0.856, with an outlier rate of 9.1% (compared to 30.5% for the Snyder method).
• Key Factors for Chen Method's Success: Its incorporation of friction velocity (u*) effectively accounts for non-uniform airflow and turbulent exchange in the greenhouse, and it does not rely on an empirical calibration coefficient (α), which varies significantly in greenhouse environments. The Chen method also offers faster calculation speed and reduced occurrence of abnormal data points.

Contributions

• This study innovatively applies the Surface Renewal (SR) method to semi-closed, actively heated Venlo-type greenhouses, distinguishing it from previous SR studies conducted in open-field environments.
• It provides a new, low-cost, and accurate quantitative tool for estimating sensible heat flux in complex greenhouse environments characterized by artificial regulation and non-uniform airflow, thereby supporting precision irrigation and accurate evapotranspiration estimation.
• The research clearly demonstrates the superior applicability and accuracy of the Chen method over the traditional Snyder method for greenhouse sensible heat flux estimation, particularly due to its integration of friction velocity and independence from empirical calibration coefficients.
• The study highlights that the stable internal environment of greenhouses (e.g., maintained temperature, isolation from precipitation/frost) positively enhances the performance and accuracy of the SR method, especially the Chen model, compared to open-field applications.

Funding

• National Natural Science Foundation of China (Grant No. 32171896).

Citation

@article{Li2025Study,
  author = {Li, Yang and Hu, Yongguang and Lu, Yongzong and Wang, Jizhang},
  title = {Study on the Estimation of Greenhouse Sensible Heat Flux Based on the Surface Renewal Method: Validation and Calculation Results},
  journal = {Agriculture},
  year = {2025},
  doi = {10.3390/agriculture15232439},
  url = {https://doi.org/10.3390/agriculture15232439}
}