Energy consumption analysis of a ground water-source heat pump for the plant factory based on TRNSYS simulation

The ground water-source heat pump system for the plant factory lacks a scientific operation strategy to solve the problem of high energy consumption in winter and summer. It is very difficult and uneconomical to change the operation conditions by experimental means to obtain actual operation data. The current study aims to build a TRNSYS simulation model of the ground water-source heat pump system of Shanghai Chongming Natural Light Plant Factory. For the heating season, the simulation of energy consumption was 2315 GJ. Compared with the actual energy consumption, the relative error is -0.98%, which indicates that the simulation results are accurate and the simulation model developed is appropriate and usable. Numerical simulations for the whole year on this basis yielded that the plant factory energy supply system operates from November to March with a heating energy consumption of 3530.84 GJ and from June to September with a cooling energy consumption of 1126.24 GJ. In most cases, the indoor temperature fluctuates within a reasonable range, but in the summer high-temperature season, the plant factory temperature will reach above 40℃, which seriously affects plant growth. After optimization, the plant factory stops production in July and August, and the system stops running, the results are that the optimized system can save 56% of the annual cooling energy consumption, totalling 767.48 GJ, which can reduce the costs by 160,318.05 RMB

Dynamics and Numerical Simulation of Contaminant Diffusion for a Non-Flushing Ecological Toilet

The poor indoor air quality (IAQ) of severely polluted toilets is associated with increased risk of severe disease. This study aimed to evaluate the overall IAQ according to the contaminant removal efficiency, volume average concentration, and breathing zone control level. The characteristics of contaminant transmission in a non-flushing ecological toilet (NFET) were analyzed using the computational fluid dynamics (CFD) methodology, and the proposed model was further validated based on experimental measurements. Both an orthogonal experimental design and CFD were used to analyze factors such as exhaust fan position (EFP), air change rate per hour (ACH), natural vent location (NVL), and grid height (G-h). The EFP and ACH were demonstrated to be the dominant factors affecting the IAQ, whereas NVL and G-h were found to play key roles. Single-factor analysis based on the significance levels of the ACH, EFP, and NVL was conducted using the CFD methodology to define three exhaust behaviors—namely, “ineffective”, “enhanced”, and “excessive”. These results provide key insights that may be used to improve the IAQ of NFETs