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New sensor technology optimizes evaporator performance especially during part load on both DX, flooded and pump circulation systems.

Number: pap. 0010

Author(s) : ELSTROEM M.

Summary

The increased requirements to reduce global warming (GWP) lead to a desire for the use of natural refrigerants. The use of natural refrigerants is associated with major challenges, like safety (R717 & R290) and poor system efficiency (R744). New measurement methods make it possible to increase safety and achieve higher energy efficiency with both zero super-heat and demand driven defrost control. The use of Superheat control has for decades been necessary for safe operation of refrigeration systems. Superheat is however an area where a lot of energy is wasted without adding any value. A new revolutionary patented technology solves one of the main challenges when using CO2 and other refrigerants. CO2/NH3 refrigerant is very dynamic and reacts strongly on small changes in load and pressure-/temperature. With the new Vapor Quality Sensor solution measuring the dryness of the vapor and the phase of refrigerant flow (two-phase flow regime) it is possible to achieve a more balanced system performance with minimum Superheat and less pressure fluctuation (Semi-Flooded operation). By this solution it is possible to control the evaporator capacity faster and more accurate within a Superheat range of 0.5 to 1.0K. The sensor measures the Vapor Quality as the ratio of the vapor and liquid in a two-phase flow. The same measuring principle (capacitive) is also used for measuring ice build-up on air coolers at operating temperature below 0°C in form of a wire mounted between some of the evaporator fins and thus defrost cycles only starts when needed (On Demand) The sensor reacts as an "X" sensor that directly measures the dryness where “X”0.0 = 100% liquid and “X”1.0 = dry vapor gas. This paper and the following presentation will describe the sensor's measuring principle, system design and the location of the sensor, as well as experiences from tests performed on both NH3 and CO2 system. A brief presentation of tests performed on CO2 systems will also be included.

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Details

  • Original title: New sensor technology optimizes evaporator performance especially during part load on both DX, flooded and pump circulation systems.
  • Record ID : 30025681
  • Languages: English
  • Source: 8th Conference on Ammonia and CO2 Refrigeration Technology. Proceedings: Ohrid, North Macedonia, Avril 11-13, 2019.
  • Publication date: 2019/04/11
  • DOI: http://dx.doi.org/10.18462/iir.nh3-co2.2019.0010

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