IIR document

Development of a compact CO2 heat pump for industrial drying.

Number: pap. n. 173

Author(s) : HASHIMOTO K., SAIKAWA M., MISUMI S., et al.


There are numerous examples of compact electric heaters used in drying processes in industrial establishments. These heaters consume considerable electricity due to the extended operating time, despite the small capacity of the individual heaters, hence the development of alternative highly efficient equipment is anticipated. In this study, we studied and developed a small capacity CO2 heat pump for drying industrial parts after washing with water. The specifications were: air outlet temperature of 85°C, heating capacity of about 3 kW, heat source (water) temperature of 30°C and COP above 3. Firstly, we calculated the theoretical COP and designed an air heating heat exchanger (i.e. gas cooler). However, we were unable to obtain an air outlet temperature of 80°C due to the lack of high pressure CO2. Secondly, we built a “breadboard prototype” based on technology developed for “ECO CUTE”. The evaluation test results showed that COP over 3 was achieved under the condition of an air heating capacity of 3 - 6 kW, air inlet temperature of 25°C, air outlet temperature of 80°C and heat source water temperature of 30°C. Thirdly, we developed a “prototype” and evaluated it in CRIEPI's environmental test facility. Consequently, the prototype operated well automatically and achieved a performance equivalent to the breadboard prototype. The heat pump may be able to reduce the power consumption to about one third of the conventional process.

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  • Original title: Development of a compact CO2 heat pump for industrial drying.
  • Record ID : 30004316
  • Languages: English
  • Source: 10th IIR-Gustav Lorentzen Conference on Natural Working Fluids (GL2012). Proceedings. Delft, The Netherlands, June 25-27, 2012.
  • Publication date: 2012/06/25


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