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Heat exchanger design by computer
Both models have an output socket for remote displays, data logger or chart recorder. Optional accessories include a set of grille hoods for volume flow measurement at supply and extract grilles. Airflow Developments Ltd, Lancaster Road, High Wycombe, Bucks HP12 3QP, UK
Heat exchanger design by computer A heat exchanger is one of the most common components of a process plant and yet, usually, each one has to be individually designed. This may involve tedious and time consuming manual calculations. However, a range of heat exchanger design, computer programmes for process plant engineers is now available as a bureau service from Scicon. They are not intended to eliminate informed judgement but to free the engineer of the more mundane tasks associated with the design. Access to the service can be via a user's own terminal or one in a Scicon regional office. The programmes can be run using a simple conversational procedure allowing the user to .concentrate on the engineering aspects without the distraction of computer technicalities. The service encompasses a variety of tasks. For thermal design and rating programmes for various heat exchangers, Scicon make available a range of programmes produced by the Heat Transfer and Fluid Flow Service (HTFS) at Harwell and the Heat Transfer Research Inc. in California. These may be applied to both shell and tube exchangers, air coolers, reboilers and cryogenic exchangers. The programmes are updated from the research being carried out at the two establishments. Mechanical design of shell and tube exchangers, calculated to ASME
Volume 3 Num6ro 3 Mai 1980
VIII and TEMA standards, is provided by STEM. This package demonstrates inconsistencies occurring between thermal requirements and mechanical calculations. For the design and rating of single or paired flanges the programme called FLANGE is used. This programme has been developed by CAD Centre in collaboration with NEL and HTFS. Vibration analysis of heat exchanger tube bundles is provided by HENVIBS (Heat Exchange Noise and Vibration System) a programme developed by Perara and Associates. This enables the engineer to prevent shell-side pressure drop, production loss due to leaking tubes and to extend the life expectancy of the heat exchanger installation. Finally, both setting plan and tubesheet layout drawings can be provided by STEM. Scicon Computer Services Ltd, Brick Close, Kiln Farm, Milton Keynes MK11 3EJ, UK
Small freeze-dryers Two laboratory/pilot freeze dryers, which can simulate all the parameters of industrial freezedrying cycles including prefreezing have been developed by Edwards High Vacuum. Called the Minifast 1700 and Minifast 3400 they have usable shelf areas of 2600 cm 2 and 5200 cm 2 respectively. This are is split between two shelves. The smaller model has a capacity for 1700 ampoules, the larger for 3400 ampoules. The manufacturers suggest that the latter would be large enough for a small-scale and semi-automated freeze drying. Pre-freezing is by direct expansion of refrigerant in the support shelves. In both models the two shelves are independantly controlled. Thus different
products may be processed separately or two different sets of parameters may be studied simultaneously. Both models have a wide range of accessories including: vacuum and temperature recorders; cam programme controllers; and on the 1700, cascade compressors with which shelf temperatures down t o - - 6 0 ° C can be achieved. Edwards High Vacuum, Manor Royal, Crawley, West Sussex RH10 2LW, UK
Getting cold in a bath A low temperature thermocirculator operating down t o - - 4 0 ° C has been announced by Churchill Instrument. Both a constant and variable temperature model is available. It is designed for use in freeze drying, low temperature techniques, thermal shock testing and low temperature calibration. The unit is driven by a 560 W (0.75 hp) compressor giving a claimed heat extraction rate at --20°C of 3159.5 kJ h 1 (750 kcal h 1). The exchanger is built into an open, stainless steel bath which has a removable insulated lid. The bath has a capacity of ~-6.5 I and the contents are continuously circulated by a glandless, magnetically
Temperature thermocirculator operating down to--40"C
129
Heat exchanger design by computer A heat exchanger is one of the most common components of a process plant and yet, usually, each one has to be individually designed. This may involve tedious and time consuming manual calculations. However, a range of heat exchanger design, computer programmes for process plant engineers is now available as a bureau service from Scicon. They are not intended to eliminate informed judgement but to free the engineer of the more mundane tasks associated with the design. Access to the service can be via a user's own terminal or one in a Scicon regional office. The programmes can be run using a simple conversational procedure allowing the user to .concentrate on the engineering aspects without the distraction of computer technicalities. The service encompasses a variety of tasks. For thermal design and rating programmes for various heat exchangers, Scicon make available a range of programmes produced by the Heat Transfer and Fluid Flow Service (HTFS) at Harwell and the Heat Transfer Research Inc. in California. These may be applied to both shell and tube exchangers, air coolers, reboilers and cryogenic exchangers. The programmes are updated from the research being carried out at the two establishments. Mechanical design of shell and tube exchangers, calculated to ASME
Volume 3 Num6ro 3 Mai 1980
VIII and TEMA standards, is provided by STEM. This package demonstrates inconsistencies occurring between thermal requirements and mechanical calculations. For the design and rating of single or paired flanges the programme called FLANGE is used. This programme has been developed by CAD Centre in collaboration with NEL and HTFS. Vibration analysis of heat exchanger tube bundles is provided by HENVIBS (Heat Exchange Noise and Vibration System) a programme developed by Perara and Associates. This enables the engineer to prevent shell-side pressure drop, production loss due to leaking tubes and to extend the life expectancy of the heat exchanger installation. Finally, both setting plan and tubesheet layout drawings can be provided by STEM. Scicon Computer Services Ltd, Brick Close, Kiln Farm, Milton Keynes MK11 3EJ, UK
Small freeze-dryers Two laboratory/pilot freeze dryers, which can simulate all the parameters of industrial freezedrying cycles including prefreezing have been developed by Edwards High Vacuum. Called the Minifast 1700 and Minifast 3400 they have usable shelf areas of 2600 cm 2 and 5200 cm 2 respectively. This are is split between two shelves. The smaller model has a capacity for 1700 ampoules, the larger for 3400 ampoules. The manufacturers suggest that the latter would be large enough for a small-scale and semi-automated freeze drying. Pre-freezing is by direct expansion of refrigerant in the support shelves. In both models the two shelves are independantly controlled. Thus different
products may be processed separately or two different sets of parameters may be studied simultaneously. Both models have a wide range of accessories including: vacuum and temperature recorders; cam programme controllers; and on the 1700, cascade compressors with which shelf temperatures down t o - - 6 0 ° C can be achieved. Edwards High Vacuum, Manor Royal, Crawley, West Sussex RH10 2LW, UK
Getting cold in a bath A low temperature thermocirculator operating down t o - - 4 0 ° C has been announced by Churchill Instrument. Both a constant and variable temperature model is available. It is designed for use in freeze drying, low temperature techniques, thermal shock testing and low temperature calibration. The unit is driven by a 560 W (0.75 hp) compressor giving a claimed heat extraction rate at --20°C of 3159.5 kJ h 1 (750 kcal h 1). The exchanger is built into an open, stainless steel bath which has a removable insulated lid. The bath has a capacity of ~-6.5 I and the contents are continuously circulated by a glandless, magnetically
Temperature thermocirculator operating down to--40"C
129