Heat pump technology has become an essential solution in the field of medium-and low-temperature heating due to its superior efficiency in converting electrical energy into thermal energy. However, owing to the lack of stable heat sources during winter in northern China, it is necessary to store the heat sources within the urban area throughout the seasons to ensure the stability of the heat provided by the heat pump system. In this study, based on the project of seasonal/daily thermal storage of river water in Guantao, a simulation model was constructed using the Transient System Simulation Tool (TRNSYS). A sensitivity analysis of the thermal energy storage unit parameters was conducted under the constraint of the fixed site area. The configurations and strategies of the daily thermal energy storage were optimized. The results show that the temperature rise of the thermal energy storage unit reaches 3.2 ℃ after 10 years of operation, effectively preventing the soil heat imbalance. The distance between the buried pipes and the depth had the greatest influence on the performance of the system. The total length of the pipes could be reduced by approximately 23% with a spacing of 4 m and a depth of 150 m. The daily thermal energy storage system should be matched to the valley power storage heat and heat release load to avoid wasting the valley power. If the storage heat power is large, the volume of the storage tank can be increased, and the flat power heat release is considered. The optimized system improves the utilization rate of valley power and reduces annual operating costs by 11.2%.

This paper presents a novel approach for evaluating the air impact on urban microclimate and building loads. Traditional software tools, such as TRNSYS and EnergyPlus, often employ the surface-to-surface method for radiation transfer calculations, which neglects the influence of air. To address this limitation, this work integrates the discrete ordinates method (DOM) with the spectral-line weighted-sum-of-gray-gases (SLW) air model to develop a microclimate energy approach. The SLW model uses outdoor temperature and humidity data to compute absorption coefficients, leveraging the air spectrum provided by the HITRAN database. The DOM is then employed to calculate both solar and infrared radiation transfers within the urban environment. A transient simulation is conducted over one year for an urban scene in Suzhou, China. The results indicate that the air impact on radiation transfer increases with rising outdoor temperature and humidity. Overall, the results demonstrate that air effects exert a non-negligible influence on building heating and cooling load calculations, with an impact magnitude comparable to the introduction of an auxiliary thermal source. This study highlights the significance of considering air properties in urban microclimate and building energy simulations for more accurate results.

To solve the problem of condensation at the radiant cooling terminal, a novel radiant cooling terminal (NRCT) based on the moisture buffering effect is proposed. The NRCT combines traditional radiant cooling terminals with solid humidity conditioning materials (HCM). On this basis, a coupled anti-condensation regulation strategy between the NRCT and the fresh air system was constructed, which utilizes the moisture buffering effect of the HCM to extend the condensation time, and reserves sufficient time for active intervention of personnel and feedback adjustment of the fresh air system. Then, the indoor air parameters are restored to normal design values as a result of the fresh air system. Meanwhile, the HCM releases the adsorbed water vapor, thereby enabling the completion of the desorption process. Using numerical simulation methods to study each step of the anti-condensation regulation strategy, the results indicate that the NRCT can effectively prevent condensation, and it can ensure that condensation does not occur within 20 min after the window is opened, even under extreme weather conditions. Moreover, the anti-condensation effect improves with the thickness increase of the HCM. However, when ensuring the prevention of condensation while expecting the best moisture adsorption effect, there is an optimal value for the thickness of the HCM. Increasing the fresh air supply volume can enable the HCM to complete the desorption process more quickly. In the final steady-state operation process, the HCM can continue to release moisture, achieving sustainable utilization of the HCM. In actual operation, the operational duration of the fresh air system during the moisture desorption process can be regulated by tracking the relative humidity of the outlet to ensure that the HCM completes the adsorption and desorption cycle. This anti-condensation regulation strategy can provide effective guarantee for the non-condensing operation of radiant cooling terminals.