Integrative environmental control using heat pumps for reductions in energy consumption and CO sub 2 /sub gas emission, humidity control and air circulation.

摘要

An integrated environmental control system with heat pumps and CO₂ enrichment equipment has been designed for a greenhouse to reduce primal energy consumption, CO₂ (or global warming) gas emission and costs for heating in winter. It is also designed for nighttime cooling in summer, and year-round controls of water vapor deficit, air circulation and CO₂ concentration. The system controls the greenhouse environment from a view point of energy and mass balances of the greenhouse and plants, using minimum electricity, water, agrochemicals, land area etc., and emitting minimum CO₂ gas and polluted water. The system is operated: (1) to maximize light utilization efficiency (or net photosynthesis) of plants during daytime by optimizing the greenhouse environment under a given solar radiation condition, and (2) to optimize developmental stage and metabolite translocation of plants by controlling mainly nighttime and daytime temperatures. Water vapor deficit and air circulation are controlled to optimize the rates of transpiration, net photosynthesis and consequently uptake of nutrients, and to minimize the spread of disease. CO₂ is enriched whenever ventilators are closed in daytime with/without cooling the greenhouse using heat pumps. This paper presents the baseline conceptual framework of the system with preliminary results.