Bo Ivar Sångfors

BoSångfors Consulting

This paper gives a short presentation of a method for the computer simulation of noise caused by the gas pulsations, created from the opening and closing of inlet and discharge ports of twin-screw compressors. The method takes into account influences from lobe combinations, wrap angle, length/diameter ratio, leakage through blowhole and clearances...

In this paper a physical model for prediction of oil-flooded twin screw compressor performance is presented and discussed. Calculation results are presented.

This data set shows that at high brine flows generated effect starts to decrease. For more information see the updated version of this data set.

These graphs show how different built-in volume ratio effects the generated electric power and the screw expander adiabatic efficiency. Inlet pressure = 15 bar Outlet pressure = 1 bar Steam quality x = 1.00 Generator efficiency = 0.95 The rotor tip speeds are from 20 m/s up to 110 m/s. As can be seen low built-in volume ratio leads to high power ou...

This paper gives a short presentation of a method for computer simulation of effects on the performance of screw compressor from injection of different liquids. The method takes into account liquid evaporation, subsonic or sonic two-phase leakage, heat transfer between liquid-gas-metal, flashing of dissolved gas, displacement of liquid volume and f...

These calculations show the performance of a HYDROGEN screw compressor which work with inlet pressure 30 bar and outlet pressure 90 bar. The effect of the injected oil rate is presented.

This graph shows the influence of different working media on the performance of a twin screw expander.

The intention of these calculations is to show the performance of a twin screw compressor working with waterlubricated rotors. The presented calculations are made in accordance with the theory presented in the Purdue paper "Computer simulation of effects from injection of different liquids in screw compressors". Input data at optimal performance. G...

The short data paper presents performance calculation of a twin screw compressor for hydrogen working with inlet pressure 30 bar and outlet pressure 90 bar.

The short data paper presents performance calculation of a twin screw compressor for hydrogen working with inlet pressure 30 bar and outlet pressure 90 bar.

Generation of electricity from low quality steam using twin screw expanders.

This data set gives which sizes are necessary when you want to generate approx. 15 MW by using 2 twin screw expanders . 1.Steam expander gives the brine flow entering 2. Ammonia ORC-expander.

The expander is a dry twin screw expander with synchronizing bearings Profile = 4+6-combination Male rotor diameter = 285 mm Female rotor diameter = 285 mm. Male rotor tip velocity = 20-120 m/s Inlet pressure = 16.201 bar. Inlet temperatures = 202 (x=1), 302 and 402 centigrade Outlet pressure = 2.7 bar Built-in volume ration Vi = 2.7 The steam supe...

This data file presents a 2 stage system consisting of a Steam Screw Expander and a R245fa Expander working in serie. The steam expander delivers the outcoming steam as brine to a R245fa-expander in a ORC-system.

As is well-known the steam quality x is very important for the performance of a steam expander. This graph is just a way to present that. The presented data set shows the generated electrical power as a function of the steam flow at various steam quality x. As is obvious the decreasing steam quality increases the necessary steam flow for generation...

In order to give more information about the effects of various built-in volume ratio Vi, when using a screw expander in an ORC-system these calculations are presented.

In order to give some more information about the effects of different working media on the performance of a twin screw expander with the diameter 285 mm these calculations are presented. As is shown the choice of working media is very important and determines the size of the screw expander.

As is well known it is important to have a good heat transfer from the brine to the working media. The intention of this short data set is to show how the brine outlet temperature effects the needed brine flow.

In order to show the importance of the feed pump losses in an ORC-system using working media of different quality X this short paper sheet is presented.

Trilateral Flash Cycle. In order to give more information about the effects of various built-in ratio at different steam quality X, when using a screw expander for generating electrical power these calculations are presented.

This short data set describes the difference between using an approx. theory compared to direct use of the program REFPROP.

The data file presents the effect of the built-in volume ratio upon the generation of Sound Pressure Level SPL from the outlet of a refrigeration Twin Screw Compressor. It is shown that the built-in volume ratio can cause high noise levels if not properly designed.

This data set shows an easy method to predict the generated power from a twin screw expander working with 100 % adiabatic efficiency. The presented enthalpy data in the graph are obtained from the program REFPROP. Since the enthalpy is in kJ/kg the value is representative for a screw expander working with constant inlet mass flow. As can be seen th...

In these calculations the steam mass flow is kept constant by changing the male rotor tip speed at different steam quality x. - As can be seen the generated power decreases with decreasing inlet steam quality x. Fig.1 shows that the generated effect decreases with decreasing steam quality. Fig.2 shows the necessary variation of the male rotor tip...

In order to give some feeling about the effects of different working media on the performance of a twin screw expander with the diameter 285 mm these calculations are presented. As is shown the choice of working media is very important and determines the size of the screw expander. Furthermore is shown that the media pump power consumption can be i...

This data set shows the generated electrical effect from a generator driven by a steam screw expander as a function of inlet steam quality x. Fig.1 shows the generated electrical effect as a function of the steam quality x. As is shown the generated effect is approximately the same for steam quality x > 0.2. It is also interesting to see that for...

In these calculations the steam mass flow is kept constant by changing the rotor tip velocity. As can be seen the generated power and the adiabatic efficiency increase when the steam quality increases. Correction: 7.25 ton/h is at built-in volume ratio Vi = 3 not at Vi=1.

This is a correction of the male rotor tip speed for stage 2 in the earlier uploaded data set "Using 2 screw expanders of same size for generation of power from a 2 stage Steam heat recovery system" . The new data is 30 < Vtip < 90 m/s.

In order to give some feeling about the effects of different working media on the performance of a twin screw expander with the diameter 285 mm these calculations are presented. As is shown the choice of working media is very important and determines the size of the screw expander. Furthermore is shown that the media pump power consumption can be i...

This 2-stage recovery system consists of two dry screw expanders of the same size. Stage one: Steam expander. Diam. = 285 mm, built-in volume ratio = 2.0 Stage two: R245fa screw expander. Diam. = 285 mm, built-in volume ration = 1.9

This graph is just to show the importance of having a good steam quality at the screw expander inlet. One can say that this is typical for all displacement machines - not only screw expanders.

Refrigeration Screw compressor. The presented computer simulations of pressure and gas/oil temperatures are performed in accordance with the theory and assumptions presented in the 1984 Purdue paper “Computer Simulation of the Oil Injected Twin Screw Compressor”.

This is an addition to the data file "Importance of having good steam quality x at the inlet of a Steam Screw Expander generating electric power" and "Effect of inlet steam quality X if the inlet steam mass flow is constant" earlier uploaded on Research Gate. In these calculations the steam mass flow is kept constant by changing the built-in volume...

The presented computer simulations of pressure and gas/oil temperatures are performed in accordance with the theory and assumptions presented in the 1984 Purdue paper “Computer Simulation of the Oil Injected Twin Screw Compressor”.

These graphs show the difference between using approx. method versus use of for instance Mollier chart for real gases.

This is an addition to the data file "Importance of having good steam quality x at the inlet of a Steam Screw Expander generating electric power" earlier uploaded on Research Gate. In these calculations the steam mass flow is kept constant by changing the inlet pressure and temperature. As can be seen the generated power as well as the inlet press...

The interesting in these calculations are that the built-in volume ratio = 1.0 (similar to a Roots blower). This means that the flashing during expansion takes place outside the closed control volume. i.e. the effect from flashing can be neglected. This short set of data also presents comparative calculations between a Screw Expander having built-i...

Having built-in volume ratio Vi =1.0 means that the effect of flashing or condensation during the expansion process in a closed volume can be neglected. All expansion or condensation takes place in a volume that is open to the outlet. As can be seen it is very important to have a good steam quality at the screw expander inlet

The data set presents the effect of R245fa inlet quality X upon the Performance of a Screw Expander. Most interesting is the ORC-efficiency at X-values close to zero.

This graph is just an addition to my earlier data set " Screw Expander Inlet Pressure Drop and it's Effect on Performance as a function of R245fa inlet quality X " on Research Gate The data set shows the importance of having a good quality X at the expander inlet. The decrease in performance is mostly caused by the increase in pressure drop over th...

Fig 1 shows what happens if you change the steam quality x at the inlet of the screw expander. As you can see the generated power as well as the ORC-efficiency decreases as x decreases, but the brine flow increases. As is obvious it is important to have a good quality x at the expander inlet. Brine = Water. Coolant = Water. Working medium =R245a, 0...

The first graph shows the generated electric power from a screw expander as a function of the steam flow at different inlet steam quality x. Another graph shows that at built-in volume ratio =1.0 no effect is obtained from condensation or flashing, since all condensation or flashing occur in a volume open to the compressor outlet.

In order to give more information about the effects of various steam quality X, when using a screw expander in an ORC-system these calculations are presented.

In order to give some more information about the effects of different working media on the performance of a twin screw expander with the diameter 285 mm these calculations are presented. The presented results are additional to those presented in the file " Different Working Media " uploaded on Research Gate. As is shown the choice of working media...

In order to give more information about the effects of various built-in volume ratio Vi, when using a screw expander in an ORC-system these calculations are presented. This data set presents 2 graphs, where fig.1 shows the performance as a function of the male rotor tip speed and fig.2 the performance as a function of the brine flow. The expander i...

In order to give some more information about the presented calculations in " Avoiding inlet flow choking at a Screw Expander inlet " this updated version is made. This version contains 2 graphs – very equal – but fig.1 is performance as a function of Brine flow and fig.2 is performance as a function of Male rotor tip speed. The expander is a dry sc...

This data set shows the importance of having good steam quality at the inlet of a steam expander when generating electric power.

Fig 1 and 2 show what happens if you change the brine flow but have the coolant flow constant. As is obvious it is important to have enough coolant flow if you want an efficient ORC performance.

Estimated Performance of a Waste Heat Recovery System Stage 1: Steam Screw Expander Stage 2: ORC using Screw Expander and R134a as the working medium. Why not change the working media from R134a to R245fa? Then it is necessary to change the rotor diameter from 285 mm to 403 mm to get the same performance. - Why not use a turbine instead, since the...

This graph shows the effect of the steam quality at the inlet. With decreasing steam quality the mass flow through an expander increases. Decreasing steam quality means increased density. Can easily be seen in for instance REFPROP.

This show how the different leakages are effected when the axial seal clearnace is increasing.

This show how the different leakages are effected when the axial seal clearnace is increasing in a Tri-sector Rotary Heat Exchanger.

In order to recover the waste heat from wet flue gas in a Power station a rotary heat exchanger can be used. These calculations show that the heat transfer is much higher for a rotary heat exchanger than a recuperative. This because the rotary heat exchanger can evaporate back the condensed water to the air.

When SCR for reduction of NOx-emissions is used in coal-fired power stations the flue gas entering the rotary heat exchanger for waste heat recovery contains sulhpuric acid and ammoniumbisulfat. Therefore a heat exchanger must be designed in such a way that operational problems are reduced.

These calculations are made with the same theory as reported in the paper “Modeling, Measurements and Analysis of Gas-Flow Generated Noise From Twin-Screw Compressors” . This is an example with a large chamber after the outlet. The Fourier analysis is based on computed data in the pipe after the large chamber.

Results from discussions with Elvedin Mujic, City University London. As can be seen reduction of SPL also causes decrease of the adiabatic efficiency.

This is a copy of the email I sent to 'Nabil Elsharif at Northumbria University, UK' as an answer to his question. Hello, I send you a very simple picture of a standard set-up of cooling flanges. If you expose the upper side to incoming heat from the sun and then cover the end of the flanges you get many boxes. Then flow air through the channels yo...

These computer simulations are using a modified theory of that described in the papers:“Computer Simulation of Effects from Injection of Different Liquids in Screw Compressors”, Purdue 1998“ and "Numerical calculation of effects from injection of different liquids in twin screw compressors”, VDI 1998. In these calculations two screw compressors us...

The channels inside this type of sun collectors consists of rectangular channels. These computer simulations are made for 3 different designs as can be seen in the picture. Notice that it is the short side that is towards the incoming heat from the collector area. The increased heat transfer to the air in the channels is caused by the heat conducti...

This shows the importance of having a good Steam Quality X at the inlet of a Screw Expander

This shows the importance of having a good Steam Quality X at the inlet of a Screw Expander.

This paper gives a short presentation of a method for computer simulation of effects on the performance of screw compressor from injection of different liquids. The method takes into account liquid evaporation, subsonic or sonic two-phase leakage, heat transfer between liquid-gas-metal, flashing of dissolved gas, displacement of liquid volume and f...

In this paper a numerical method for prediction and analysis of oil-free and oil-flooded screw compressor performance is presented. The model includes inlet and discharge dynamics, leakage throughout the machine, and the thermodynamics within the thread volumes and leakage paths.