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ABSTRACT
Improving the overall energy efficiency of thermodynamic cycles relies heavily on the replacement of traditional pure fluids with zeotropic mixtures. The selection of the optimal components within the zeotropic mixture depends on the specific operating conditions of the thermodynamic cycle. Therefore, significant enhancements in performance can be achieved across varying operating conditions by effectively controlling the composition of zeotropic mixtures in the cycle. According to the gas-liquid equilibrium characteristics of the zeotropic mixtures, the adjustment of the medium components and the boundary conditions can be realized if the components can be adjusted through the gas-liquid separation. In this study, a novel device is proposed for automatically regulating the speed of gas-liquid separation in order to separate the components of the zeotropic mixtures. The CFD simulation was utilized to analyze the structural parameters and boundary conditions that impact the efficiency of gas-liquid separation. The results indicate that the adjustable mass flow range of the optimal structure is broadened by 5.5 times compared to conventional gas-liquid separation devices, ranging from 0 kg/s to 0.15 kg/s. Additionally, within this range, the gas-liquid separation efficiency exceeds 95%, representing a 10% improvement over traditional phase separators.
Nomenclature
| c | = | Specific heat capacity (kJ/(kg |
| COP | = | Coefficient of Performance (-) |
| d | = | Diameter of the horizontal tube (mm) |
| D | = | Diameter of the cylinder (mm) |
| di | = | Diameter of the ERT (mm) |
| H | = | Height of the device (mm) |
| L | = | Length of the horizon tube (mm) |
| M | = | Enthalpy (kJ/kg) |
| m | = | Mass flow rate (kg/s) |
| P | = | Pressure (MPa) |
| Q | = | Quality (-) |
| T | = | Temperature (K) |
| V | = | Viscosity (Pa*s) |
| W | = | Power (kW) |
| X | = | Component (-) |
| h | = | Activating height |
| ρ | = | Density (kg/m3) |
| Greek symbols | = | |
| Δ | = | Difference |
| η | = | Efficiency |
| ρ | = | Density (kg/m3) |
| Subscripts | = | |
| 1,2 | = | Outlet 1,2 |
| 0 | = | Mixture Inlet |
| a | = | Component a |
| b | = | Component b |
| c | = | Component c |
| d | = | Component d |
| ’ | = | TLSD |
| G | = | Gas |
| G,in | = | Gas of Inlet |
| G1 | = | Gas of Outlet 1 |
| G2 | = | Gas of Outlet 2 |
| L | = | Liquid |
| L,in | = | Liquid of Inlet |
| L1 | = | Liquid of Outlet 1 |
| L2 | = | Liquid of Outlet 2 |
| op | = | Optimal |
| Abbreviations | = | |
| ALSD | = | Advanced Gas-liquid Separation Device |
| AR | = | Adjustment Range |
| CCP | = | Combined cooling and power cycle |
| CFD | = | Computational Fluid Dynamics |
| CHPWH | = | Conventional Heat Pump Water Heater |
| ERT | = | effusion regulating tube |
| LHPWH | = | Liquid-separation Heat Pump Water Heater |
| ORC | = | Organic Rankine Cycle |
| SIMPLE | = | Semi-Implicit Method for Pressure Linked Equation |
| TLSD | = | Traditional Gas-liquid Separation Device |
| VOF | = | Volume of Fluid |
Disclosure statement
No potential conflict of interest was reported by the author(s).