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Comparison of approximation-assisted component modeling methods for steady state vapor compression system simulation.

Number: pap. 2460

Author(s) : HUANG R., LING J., AUTE V.

Summary

When conducting a steady-state modeling of vapor compression cycle, an accurate, fast and robust heat exchanger model is critical for the robustness of the cycle simulation. In such simulations, the heat exchanger models are often the most time consuming components and moreover, if those models are black-box or third party provided, the simulations can be plagued by severe non-linearities. This paper investigates and compares two approximation-assisted (AA) heat exchanger (HX) modeling approaches, Kriging-based black box metamodel and kriging-assisted (AA) three zone model, with the distributed parameter approach being the baseline. The former approximates the heat exchanger behavior given a set of results from the baseline model. The latter approximates the lumped parameters of each phase, and calculates the outlet states based on energy conservation equations. To better understand the two methods, the approximated refrigerant side and airside results were verified using 10,000 operating points from an evaporator and a condenser. The verification shows that the mean deviation of pressure drop and enthalpy change is 1.65%, and 0.51% for the Kriging metamodel, and 1.56% and 1.41% for the three zone model. For both approximation-assisted models, the mean SHR deviation is 0.53%. For the condenser simulation, the approximation results show larger deviations when the HX outlet is two-phase and near saturation line. For the evaporator approximation, the three zone model causes larger deviation when the HX has non-uniform outlet enthalpy. The approximation-assisted modeling approaches were used in a steady-state, component-based system solver to simulate the performance of a four-component vapor compression system. With the Kriging metamodel, system coefficient of performance (COP) was under-predicted by 1.30%, 1.39% and 1.06% for ASHRAE A, B and C tests, respectively. With the three zone model, COP was over-predicted by 0.39%, 0.39% and 4.77% for the three tests respectively.

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Pages: 10

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Details

  • Original title: Comparison of approximation-assisted component modeling methods for steady state vapor compression system simulation.
  • Record ID : 30024566
  • Languages: English
  • Source: 2018 Purdue Conferences. 17th International Refrigeration and Air-Conditioning Conference at Purdue.
  • Publication date: 2018/07/09

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