www . refrigerationandaircon . co . za RACA Journal I July 2024 43
Technical available for download , including the polynomial needed to calculate power consumption , refrigerating capacity , current consumption and refrigerant mass flow . Further self-explanatory tabs in BITZER SOFTWARE guide the user to more in-depth technical data , such as the application limits and dimensional drawings , as well as available accessories for the compressor .
COMBINE ADDITIONAL SYSTEM COMPONENTS AND ACCESSORIES WITH EASE From oil separator and oil cooler through compressor protection device and frequency inverter to motor and coupling for open drive compressors – once a compressor has been selected , BITZER SOFTWARE automatically suggests options to optimise the energy efficiency of the system with co-ordinated components . In the case of the CSHP compressor in the example , K series condensers are available . With water as a coolant and a water inlet temperature of + 30 ° C , the type K3803P ( two pass ) with a condensing capacity of 381kW is suggested . Just like with the compressor design , additional useful information about the chosen accessory is available under ‘ Technical data ’, ‘ Dimensions ’ and ‘ Documentation ’ in the menu .
EVAPORATOR DESIGN MADE EASY BITZER SOFTWARE is just as intuitive and helpful when it comes to designing an evaporator . With SQD shell and tube evaporators , an important new product group has been added to the software . These direct expansion evaporators are individually adaptable , deliver high levels of efficiency with their quadratic cross sections and meet current efficiency requirements . That is why the user in the example chose an SQD evaporator with a capacity of 303kW . It only takes a few clicks to complete the design . The chosen inlet temperature of + 12 ° C and outlet temperature of + 7 ° C are entered under ‘ Heat transfer fluid parameters ’ and the following parameters are entered under ‘ Refrigerant parameters ’:
• Condensing temperature ( dew ) + 38 ° C
• Subcooling 3 K
• Evaporating temperature ( dew ) + 4 ° C
• Superheating 5 K ( usable )
• Pressure drop target for optimal refrigerant distribution with propane under the given operating conditions : 200 kPa
A maximum or target pressure drop can be entered for both sets of operating conditions . Click on the ‘ i ’ symbol for more information . The software can compare a wide range of potential combinations to find the optimal solution for every application . For example , other specifications , such as shell size or tube length , can be selected in the design settings . The calculation then displays multiple compatible evaporators for the office building ’ s planned single-circuit air conditioning system .
The following aspects must be taken into consideration when selecting a specific model :
• What is the desired margin ( difference between the required and calculated evaporation
• temperature )?
• How long can the evaporator be ( tube length )?
• What volume / mass flows are suitable ?
• What is the desired pressure drop ?
For the air-conditioning system in the example , the optimal evaporator proves to be the SQD2513114-11-6035 with a 3 943mm tube length and approximately 1 % margin . Once all the necessary system components have been selected , all calculations can be exported in PDF format or saved in the software directly for use at a later date after the user has logged in via myBITZER . RACA
SOURCE : Supplied by BITZER
www . refrigerationandaircon . co . za RACA Journal I July 2024 43