Using Power Plant Discharge Water in Controlled Environment Greenhouses. Progress Report 2

摘要

TVA's waste heat utilization program identifies potential uses of the low-grade energy contained in the condenser cooling water discharged from power plants and develops and demonstrates technology to utilize this energy in efficient agricultural and aquacultural systems. Focus is on progress made in developing a system to utilize waste heat energy in an environmental control system for greenhouse production. Waste heat greenhouse developmental work has been conducted in a pilot-scale greenhouse at Muscle Shoals, Alabama. It uses an electric boiler to simulate condenser cooling water temperatures and is a preliminary step to a broader program. The facility is a conventional 7.3- by 30.5-meter glass-glazed structure that has been equipped with a waste heat environmental control system. A direct-contact evaporative pad is used in both heating and cooling. Heating is achieved by recirculating saturated air through the evaporative pad over which warm water is flowing. During cooling, the greenhouse air is vented to the atmosphere, and ambient air is drawn through the pad system to provide evaporative cooling. This amount of heating or cooling is controlled by louvers allowing either recirculation or venting of the greenhouse air. A fin-tube heat exchanger is available for use in reducing greenhouse relative humidity. The effectiveness of the waste heat environmental control system was characterized over a yearly range of ambient conditions, water temperatures, water and air flow rates, and fin-tube flow rates. The environmental data and interpretations presented are concerned mainly with characterizing operation under the most adverse ambient conditions encountered.