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• This study presents a new approach for the application of shallow geothermal energy. • Difference in temperatures of heat pipe systems with different diameter of vertical part is insignificant. • The heat resistance of the heat pipes only accounted for approximately 1% of the total thermal resistance. • The maximum heat transfer power of the heat pipe is 202 W. Owing to the depletion of global fossil energy and the increasing environmental awareness of environmental protection, the use of shallow geothermal energy has been receiving widespread attention. In this study, two sets of groundwater-based heat pipe (GBHP) systems were fabricated to explore the application of heat pipes in shallow geothermal energy and tested through lawn heating experiments during the winter. Results of the experiment showed that the vertical diameter of the heat pipe did not have any significant effect on its heat transfer performance, and the maximum difference in temperature between the horizontal section of the east and west heat pipes during the observation period was 1.6 °C. Furthermore, the heat pipe exhibited good isothermicity with a constant operation, with the average temperature difference between the condensation and evaporation sections were 2.1 °C. The heat pipe also exhibited good thermal conductivity, the thermal resistance accounting for only 1% of the total thermal resistance in the heat transfer process. The maximum heat transfer power of a single heat pipe was found to be 202 W. This study presents a new approach for the application of shallow geothermal energy. [ABSTRACT FROM AUTHOR]

To investigate the changes in colour and chlorophyll levels in vacuum-precooled green beans during storage, kinetic models and shelf life prediction models of these quality indices were established by reaction kinetics and the Arrhenius equation. Linear regression analysis was used to study the changes in colour and chlorophyll levels during 12 d of storage at 0 °C, 5 °C, 10 °C and 25 °C, and the relationship between chlorophyll level and total colour difference (ΔE) was also determined. The results showed that the colour and chlorophyll levels retained in vacuum-precooled green beans were better than those in the control group during storage. A linear regression analysis revealed that the change rate constants of colour parameters (L*, a*, b* and ΔE) and chlorophyll levels followed the Arrhenius law dependence on temperature. Colour and chlorophyll levels were successfully described by zero-order and first-order reactions, respectively. In addition, the shelf life based on ΔE and chlorophyll level changes of 10% was similar to that at a cut-off score of 6 by sensory evaluation. It was suggested that the kinetics model could accurately predict the shelf life and changes of colour and chlorophyll levels in vacuum-precooled green beans during storage. • Vacuum precooling resulted in higher retention colour of green beans during storage. • Kinetics modelling was used to map green beans color changes during storage. • The applicability of the Arrhenius law during storage was investigated. • Chlorophyll was a predictor of colour quality index during storage. [ABSTRACT FROM AUTHOR]