Development of Plastic Heat Exchangers for Sea Solar Power Plants.

摘要

Conceptual designs of heat exchangers for the sea solar power plant using lost cost plastic surfaces are evaluated. Composite walls of conductive,filled high density polyethylene and multilayered thin films of impermeable plastics are used as the reference material. Plate surfaces using thin falling films for evaporation and condensation of ammonia are identified as the least expensive concept. Horizontal tubular units are considered but cost and complexity are greater. Cost of heat exchangers for a 240MW (gross) ammonia plant is estimated at $47/kw which includes replacement of plastic surface twice during a 30year plant life. Largest cost component is steel work at 56% for the plate unit and 66% for the tubular unit. Average overall heat transfer coefficients of 300Btu/hr. (ft squared) F (clean) are feasible for ammonia heat exchangers. Prospects for successful development appear to be good. Technical aspects needing further refinement include:thermal conductivities of filled plastics;working fluid film coefficients and pressure drops;long term creep and environmental stress cracking resistance of filled plastic composites.