2008 Volume 48 Issue 4 Pages 540-548
A waste-heat transportation system that uses a phase change material (PCM)—the so-called trans-heat (TH) system—is considerably attractive from the viewpoint of saving energy because manufacturing industries such as the steelmaking industry continue to emit high-temperature waste heat. The aim of this paper is to study the feasibility of the TH system from three viewpoints—energy requirement, exergy loss and CO2 emissions—which affect the heat source and heat storage materials in the TH system. The TH system, which recovers waste heat and supplies hot or cold water, is comparatively evaluated under reasonable assumptions such as the temperature of the waste heat is 200°C and that of the supplied water is 50°C or 7°C, the transportation distance is 20 km and the laden weight of the container is 2.4·104 kg (weight of the PCM=1.75·104 kg; weight of the heat transfer oil=2.5·103 kg). The following results are obtained: The latent heat of erythritol supplies the largest amount of heat, 5.31 GJ at 50°C, in the TH systems. For supplying hot water at 50°C, the energy requirement of the TH system with erythritol is 7.7%, exergy loss is 8.1% and CO2 emission is 20.2% as compared to those of the conventional system with kerosene on site. For supplying cold water at 7°C, the energy requirement of the TH system with erythritol is 12.0%, exergy loss is 12.0% and CO2 emission is 26.6% as compared to those of a conventional absorption chiller that uses natural gas as the heat source.
