EFPLAB2: Radial Compressor

EFPLAB2 Lab Experiment: Radial Compressor

Animation Laboratory Test Setup

Bei Bedarf Zusatzinformationen Einblenden.

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Operating characteristics of the radial compressor

In order to visualise the operating characteristics of the radial compressor in the diagram, you can display up to 5 operating curves . Any further recording/measuring of operating curves leads to a step-by-step replacement of the already shown curves in the order of creation.

The measurement of an operating characteristic curve consists of 5 operating points recordings of the radial compressor. The first operating point is measured without throttling the volume flow. At the following measurements the throttle is increasingly closed. Based on the measurements at the operating points, an operating characteristic curve of the radial compressor for constant speed can be drawn in the operating characteristic diagram.

The diagram can be zoomed in by dragging a zoom window with the left mouse button over the preferred area or by double-clicking on the diagram.

Calculation table I (for the previous measured operating point)

The calculations in table I are based on the measured data of the previous operating point. In table I the mass flow, the pressure ratio and data for the isentropic comparison case (see p, v diagram) are determined.

Expansion Number: (κ = 1.4)

ε = {(\frac{κ \cdot {(\frac{p_{1}}{p_{0}})}^{\frac{2}{κ}} \cdot (1 - {(\frac{p_{1}}{p_{0}})}^{\frac{κ - 1}{κ}})}{(κ - 1) \cdot (1 - \frac{p_{1}}{p_{0}})})}^{\frac{1}{2}} = 0.9931 [-]

Intake Air Mass Flow (C = 0.992, E = 1)

\dot{m} = C \cdot E \cdot ε \cdot \frac{π}{4} \cdot d_{1}^{2} \cdot \sqrt{2 * (p_{0} - p_{1}) \cdot ρ_{0}} = 1.234 \frac{k g}{s}

Intake volume flow

\dot{V} = \frac{\dot{m}}{ρ} = 0.185 \frac{m^{3}}{s}

Pressure Ratio

π = \frac{p_{2}}{p 1} = 1.0183

Isentropic Temperature 2

T_{2 s} = T_{1} \cdot {(\frac{p_{2}}{p_{1}})}^{\frac{κ - 1}{κ}} = 293.5asdf K

Isentropic Efficiency

η_{s} = \frac{T_{2 s} - T_{1}}{T_{2} - T_{1}} = 0.454545

Variation of the Input Parameter

With the slider you can vary the speed (revolutions per minute) of the radial compressor. The variation of the input parameter has no influence on a running measurement, but the initial values of the following measurement can be picked.

Impeller Revolutions per Minute n_Impeller = min^-1

p, v - Diagram (for the previous measured operating point)

In p, v - diagram, the specific reversible pressure change work is recorded for each measured operating point (polytropic compression). For comparison, the specific reversible pressure change work of an isentropic compression with the same pressure ratio is displayed.

The diagram can be zoomed in by dragging a zoom window with the left mouse button over the preferred area.

Calculation table II (for the previous measured operating point)

The calculations in table II are based on the measured data of the previous operating point, as in table I. The calculation of the compressor efficiency and dissipation flow are listed step by step.

Polytropic Exponent

n = \frac{l n (\frac{p_{2}}{p_{1}})}{l n (\frac{p_{2}}{p_{1}}) - l n (\frac{T_{2}}{T_{1}})} = 1.5444

Specific Reversible Pressure Change Work (R_i = 287.21 [J/(kg K)] )

w_{p 12 r e v} = \frac{n \cdot R_{i}}{n - 1} \cdot (T_{2} - T_{1}) = 251.9 \frac{k J}{k g}

Pneumatic Power

P_{p n} = P_{12, r e v} = \dot{m} \cdot w_{p 12 r e v} = 5000 W

Compressing Power (c_p = 1005.2 [J/(kg K)] )

P_{12} = Δ {\dot{H}}_{12} = \dot{m} \cdot c_{p} \cdot (T_{2} - T_{1}) = 5251 W

Specific Technical Power

w_{t 12} = \frac{P_{12}}{\dot{m}} = 251.9 \frac{k J}{k g}

Dissipation Flow

{\dot{J}}_{12} = \dot{m} \cdot (w_{t 12} - w_{p 12 r e v}) = 5251 W

Compressor Efficiency

η_{c o m p r} = \frac{w_{p 12 r e v}}{w_{t 12}} = 81.4 %