# Bench Tests and CFD Simulations of Liquid–Gas Phase Separation Modeling with Simultaneous Liquid Transport and Mechanical Foam Destruction

^{1}

^{2}

^{3}

^{4}

^{5}

^{*}

## Abstract

**:**

## 1. Introduction

- No clear conviction whether the application of rigorous optimization techniques is correct, e.g., due to uncertainties related to the system parameters (physical properties).
- No evidence that hardware costs can be reduced when practically using optimization results, especially in the early stages of conceptual design.
- Problems with the proper definition of the tasks, including the determination of decision variables and existing constraints.
- Difficulties in estimating the necessary preparation time and calculations in situations with tight timeframes for project implementation. This is often directly related to the robustness of numerical algorithms and their reliability (highly nonlinear systems, complex systems of equations), for which it is difficult to accept possible preliminary assumptions [22,23,24,25].

## 2. Background and Description of the Study Approach

- Disturbances to the proper operation of conventional pumps, resulting from the variability of liquid inflow (reduction in mass flow) to the rotors.
- Mass fluctuation of the liquid flowing into equipment on the process line, causing difficulties in maintaining the required process parameters.
- Unstable flow in pipelines leading to measurement errors for flow rate, liquid density, and pressure, resulting in incorrect input data for automatic process control.

## 3. Materials and Methods

- Volume flow $\dot{Q}$ = 8.0–12.0 m
^{3}/h. - Outlet pressure p
_{2}= 1.0–1.5 bar.

^{−1}. The potential users of the pump include primarily small producers of natural foods, including drinks, fruit and vegetable juices, and ecological dairy products.

#### 3.1. Research Stand

_{n}) equals 50 mm (c) control damper installed between the tanks. The discharge side of a pump had a 50 mm pipeline, which returns the liquid to the main tank. It also has a 50 mm control throttle (d) and sight glass (e). A d

_{n}= 25 mm pipeline discharges air and residual liquid into the intermediate tank.

_{1}) type PMP21 with a measuring range of 1–10 bar was mounted at the pump inlet. A pressure sensor (p

_{2}) type PMP21 with a measuring range of 0–10 bar was mounted on the discharge pipeline. In addition, the stand was equipped with a flow meter ($\dot{Q}$) Promag10D (2” with a measurement range of 2.1–60 m

^{3}/h). It was possible to measure the demand for electric power on the stand. An N = 11.0 kW pump motor was used, controlled by an inverter.

#### 3.2. Computational Fluid Dynamics Model Assumptions

_{1}= 998.2 kg/m

^{3}and ρ

_{2}= 1.22 kg/m

^{3}, respectively, and remained in thermal equilibrium. The roughness of the hydraulic system was omitted from the calculation model. The simulations were conducted until the moment of flow stabilization and mass stream equalization, or until there were no further periodic changes in flow.

#### 3.3. Computational Fluid Dynamics Simulations and Rotor Bench Tests

^{5}Pa) and it would have a low impact on the durability and sealing of the pump housing.

_{2}= 1.0 bar and liquid volume flow $\dot{Q}$ = 23.9 m

^{3}/h.

#### 3.4. Computational Fluid Dynamics Simulations and Pump Bench Tests

#### 3.5. Bench Tests

- Clean water medium.
- Free flow of liquid to the pump from the intermediate tank to the pump.
- The water does not fill the entire section of the inlet stub.
- The inflow is uneven.
- Air enters the pump chamber.

_{2}= f($\dot{Q}$). are shown by marking the degree of dispersion in each area. Figure 11 shows pictures of the liquid flow in the discharge pipeline for three selected parameters of the pump operation: (A)—low dispersion; (B)—intermediate dispersion; (C)—high dispersion.

_{2}= 0.4–0.6 bar), no water ring is formed in the impeller (3). This causes the outlet liquid to have a high degree of dispersion, whereas for back pressures in the range of p

_{2}= 0.8–0.9 bar the liquid has a low degree of dispersion.

## 4. Results and Discussion

_{2}= 0.85 bar and $\dot{Q}$ = 7.1 m

^{3}/h (average pressure and average mass flow of area A as shown in Figure 12); SYM 2—intermediate step, where p

_{2}= 0.72 bar and $\dot{Q}$ = 16.8 m

^{3}/h (average pressure and average mass flow of area B as shown in Figure 12); SYM 3—high step, where p

_{2}= 0.46 bar and $\dot{Q}$ = 32.7 m

^{3}/h. During the simulation for SYM 1 and SYM 2 it was necessary to correct pressure p

_{2}: for SYM 1 from 0.85 bar to 0.75 bar and for SYM 2 from 0.79 bar to 0.70 bar.

- (a).
- For water pumping tests without a foam breaking impeller, the values were from N = 1.3 kW for $\dot{Q}$ = 15 m
^{3}/h to N = 2.5 kW for $\dot{Q}$ = 40.2 m^{3}/h. - (b).

^{3}/h (work area A) for the liquid-foam mixture (at the pump inlet) and foam-free liquid at the outlet port.

## 5. Summary

## Author Contributions

## Funding

## Institutional Review Board Statement

## Informed Consent Statement

## Data Availability Statement

## Conflicts of Interest

## Nomenclature

$Q$ | volumetric flow rate, m^{3}/h |

$\dot{m}$ | mass flow, kg/s |

p1 | inlet pressure, bar |

p2 | outlet pressure, bar |

ρ1 | water density, kg/m^{3} |

ρ2 | air density, kg/m^{3} |

N | electrical power, kW |

n | rotation speed, min^{−1} |

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**Figure 1.**Schematic diagram of the skimming pump: 1—casing; 2—baffle plate; 3—liquid pumping rotor; 4—foam breaking rotor.

**Figure 2.**Axionometric drawing of the tested pump: 1—casing; 2—baffle plate; 3—liquid pumping rotor; 4—foam breaking rotor.

**Figure 3.**Components of the test stand: a—main tank; b—intermediate tank; c, d—control throttle; e—pipe sight glass; p1, p2—pressure sensors; $\dot{Q}$—flow meter.

**Figure 4.**View of the test stand; (

**a**)—general vie of the stand, (

**b**)—pump section, (

**c**)—measuring devices.

**Figure 8.**Diagram of changes in lifting height p

_{2}as a function of pump $\dot{Q}$ volume flow in the impeller bench test.

**Figure 9.**Liquid jet profiles in the area of the pump outlet port for both impeller designs: primary impeller (

**left**), impeller with larger diameter (

**right**).

**Figure 10.**Results of the pump station tests. Working points p

_{2}= f($\dot{Q}$) show the degree of dispersion in areas A, B, and C.

**Figure 11.**Liquid images for three two-phase flow conditions. (

**A**)—low dispersion; (

**B**)—intermediate dispersion; (

**C**)—high dispersion.

**Figure 13.**View from the rotor front with low pressure zone and water ring; (

**SYM 1**), (

**SYM 2**), (

**SYM 3**).

Simulation/Working Point | ||||||
---|---|---|---|---|---|---|

Parameter | 1 | 2 | 3 | 4 | 5 | 6 |

p1, bar | 0.1 | 0.1 | 0.1 | 0.1 | 0.1 | 0.1 |

p2, bar | 0.7 | 0.8 | 0.9 | 1.0 | 1.1 | 1.2 |

$\dot{Q}$, m^{3}/h | 30.8 | 29.4 | 26.7 | 23.9 | 18.6 | 15.3 |

$\dot{m}$, kg/s | 8.55 | 8.16 | 7.41 | 6.63 | 5.15 | 4.25 |

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**MDPI and ACS Style**

Tomtas, P.; Skwiot, A.; Sobiecka, E.; Obraniak, A.; Ławińska, K.; Olejnik, T.P.
Bench Tests and CFD Simulations of Liquid–Gas Phase Separation Modeling with Simultaneous Liquid Transport and Mechanical Foam Destruction. *Energies* **2021**, *14*, 1740.
https://doi.org/10.3390/en14061740

**AMA Style**

Tomtas P, Skwiot A, Sobiecka E, Obraniak A, Ławińska K, Olejnik TP.
Bench Tests and CFD Simulations of Liquid–Gas Phase Separation Modeling with Simultaneous Liquid Transport and Mechanical Foam Destruction. *Energies*. 2021; 14(6):1740.
https://doi.org/10.3390/en14061740

**Chicago/Turabian Style**

Tomtas, Paweł, Amadeusz Skwiot, Elżbieta Sobiecka, Andrzej Obraniak, Katarzyna Ławińska, and Tomasz P. Olejnik.
2021. "Bench Tests and CFD Simulations of Liquid–Gas Phase Separation Modeling with Simultaneous Liquid Transport and Mechanical Foam Destruction" *Energies* 14, no. 6: 1740.
https://doi.org/10.3390/en14061740