Journal of Drive and Control (드라이브 ㆍ 컨트롤)

The Korean Society for Fluid Power and Construction Equipment (유공압건설기계학회)
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Transient Response Analysis of a Control Valve for CO2 Refrigerant

CO2냉매용 제어밸브의 응답 특성

  • Kim, Bo Hyun (Department of Mechanical System Engineering, Graduate School of Pukyong National University) ;
  • Jang, Ji Seong (Department of Mechanical System Engineering, Pukyong National University)
  • Received : 2018.08.28
  • Accepted : 2018.10.02
  • Published : 2018.12.01
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Abstract

Pilot operated control valve for $CO_2$ refrigerant is a valve that can perform various functions according to the user's intention by replacing pilot units, widely used for flow rate, pressure, and temperature control of refrigeration and air conditioning systems. In addition, $CO_2$ refrigerant, that requires high pressure and low critical temperature, can be installed and used in all positions of the refrigeration system, regardless of high or low pressure. In this paper, response characteristics are modeled and analyzed based on behavior of the main piston of the pilot-operated control valve. Although various factors influence operation of the main piston, this paper analyzes the effect of equilibrium pressure depending on valve installation position and application, and inlet and outlet orifice size of the load pressure feedback chamber to determine feedback characteristics of the main piston. As a result, it was possible to quantitatively analyze the effect of change in equilibrium and load pressure feedback chamber flow path size on the change in main piston dynamic and static characteristics.

Keywords

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Fig. 1 Structure of a CO2 control valve

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Fig. 2 Schematic diagram of a CO2 control valve

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Fig. 3 Change of P3 according to change of P4

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Fig. 4 Frequency response of piston displacement due to the variation of d23(P40: 49.88bar)

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Fig. 5 Bandwidth and natural Frequency of piston displacement due to the variation of d23(P40: 49.88bar)

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Fig. 6 Step response of piston displacement due to the variation of d23(P40: 49.96bar)

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Fig. 7 Step response of piston displacement due to the variation of d23(P40: 49.80bar)

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Fig. 8 Step response of piston displacement due to the variation of P20(d23: 0.7mm)

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Fig. 9 Step response of piston displacement due to the variation of P20(d23: 1.1mm)

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Fig. 10 Step response of piston displacement due to the variation of P20(d23: 1.5mm)

Table 1 Physical parameters of a CO2 control valve

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