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Heat bus for the tropics: exergy analysis of coupling decentralised chillers with central cooling towers.

Number: pap. 78

Author(s) : BRUELISAUER M., MEGGERS F., ENGLER R., et al.

Summary

High humidity and temperature in the tropics are above accepted indoor climate conditions, necessitating the removal of heat against the natural potential difference. Under the Low Exergy paradigm, the objective is to minimise not only this heat flow but also to decrease the heat rejection temperature for the air-conditioning system thereby increasing its efficiency. Air-cooled split-type condensers are most commonly used but inherently inefficient due to the high condenser temperature. We propose a system where decentralised water-cooled condensers are connected to an evaporative cooling tower by a hydraulic heat bus system. This paper investigates the critical parameters for the overall performance of this novel system by evaluating different design scenarios for a case study in Singapore and assesses the system in relation to air-cooled condensers. We found that the pumping exergy for the heat bus represents only a very small part of the total exergy demand as long as the hydraulic network is judiciously designed. Choosing a larger box size for the cooling tower than strictly necessary results in lower fan power and lower condenser temperature. Compared to air-cooled systems, the heat bus system reduces total exergy demand by 39%. If sensible and latent loads are split and sensible loads are met by high-temperature cooling systems, the system COP increases to 7.9, resulting in 68% exergy demand reduction. This study shows how a simple network can unlock large saving potential for air-conditioning systems while flexibly catering to individual needs.

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Pages: 11 p.

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Details

  • Original title: Heat bus for the tropics: exergy analysis of coupling decentralised chillers with central cooling towers.
  • Record ID : 30008575
  • Languages: English
  • Source: Clima 2013. 11th REHVA World Congress and 8th International Conference on Indoor Air Quality, Ventilation and Energy Conservation in Buildings.
  • Publication date: 2013/06/16

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