New positions for an internal heat exchanger in a CO2 supercritical refrigeration plant. Experimental analysis and energetic evaluation

• A CO2 refrigerating plant working in supercritical conditions has been tested.
• Two different positions for an IHX have been experimentally analyzed.
• An improvement up to 13% in COP, and up to 12% in cooling capacity, has been reached.
• Regardless the position, a reduction up to 3.65 bar in the optimal rejection pressure has been reached.

IHX is probably, one of the most commonly alternative used to improve cooling capacity and COP in a CO2 refrigerating plant working in supercritical conditions. The “classical” position at gas-cooler exit has been analyzed by several authors with positive results. The aim of this work is to compare, from experimental approach, the energetic behavior of a refrigerating plant working with several IHX configurations: gas-cooler exit (classical position), liquid receiver exit, and in both positions at the same time. The energetic behavior includes: cooling capacity, power consumption and COP. Moreover, the discharge temperature reached on each position has been analyzed.From the experimental results, a general improvement in COP and cooling capacity has been observed regardless the position of the IHX. A maximum increment of 13% on COP has been registered working with two IHX at the same time.