Abstract
Abstract
This paper presents the detailed design and analysis of an automotive adsorption air conditioner, particularly the critical components, the adsorbent canisters, or adsorbers, and the exhaust-to-oil heater. The best adsorbent-refrigerant combination is activated carbonammonia. For the adsorber shell and tubes, austenitic stainless steel 304 has sufficient fatigue strength at 300 °C and is compatible with ammonia. Annular fins and wool inside the adsorbers are nickel-plated low-carbon steel. The exhaust-to-oil heater is of ferritic stainless steel and can withstand heating beyond 400 °C. The adsorbers, oil heater, and refrigerant reservoir are sized on the basis of the cooling requirement for a subcompact car during a typical commute, as defined in Part 1. The refrigerant reservoir provides immediate cooling upon start-up of a cold engine while the exhaust system and adsorbers are heating. A thermal reservoir containing phase-change material (PCM) allows full recharging of the refrigerant reservoir after a 20 min commute. Detailed thermal, fluidic, and mechanical analyses of the adsorbers and oil heater are performed. Eliminating the mechanical compressor increases fuel mileage by 14-18 per cent for mid-size, compact, and subcompact cars, or 4.6-6.0 per cent annually, given a 4 month cooling season. The adsorption system adds ∊3.5 per cent to vehicle mass, which reduces fuel mileage by ∊2.1 per cent. Thus, the annual benefit/cost ratio in terms of fuel mileage ranges from 2.3 to 2.7.
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