TRNFLOW – Ventilation module for TRNSYS 18

The TRNSYS thermal multi-zone building model, type 56, requires airflows between zones as input values; however, in natural ventilation systems, these depend on wind pressures and the inside and outside temperatures. To account for this situation, coupling with an airflow model is an absolute must.

TRNFLOW integrates the multi-zone airflow model COMIS into type 56. An internal solver, optimized for this task, iterates in each time step between the two models until their solutions are consistent. The existing GUI TRNBuild was extended to allow for entry of the data needed for the airflow model, ensuring a user-friendly coupling of the applications.

TRNFLOW represents a major step forward in building simulation with TRNSYS.

Advantages

TRNFLOW is a tool allowing for quick and easy calculation of natural ventilation, passive night cooling, double facades and exhaust airshafts. No new input file structure or user interface has to be learned. It is simply an expansion of the familiar, user-friendly TRNBuild application. Due to the full integration, the required input data is greatly reduced and less prone to error.

The newly developed internal solver is highly stable. Due to integrated automatic optimization of convergence, users are no longer bothered with numerical questions.

Features

The current version of TRNFLOW includes the following performance features:

• Calculation of the air exchange taking into account:
  • Window ventilation
  • Infiltration/exfiltration
  • Airflow between rooms
  • Mechanical fresh and exhaust air
• Multi-zone fluid simulation with:
  • External and internal knots
  • Flow resistances (links)
• Airflow generators are:
  • Wind pressures
  • Temperature differences (chimney effect)
  • Mechanical ventilation
• Standard inputs are:
  • Wind speed
  • Wind direction
  • Atmospheric pressure
  • Pollutant concentration of outdoor air
  • In/out of TRNFLOW
• TRNFLOW outputs:
  • Single thermal zone
  • Group of thermal zones
  • Auxiliary nodes
  • Complete building
  • External nodes
  • Airlink