Green Sprinkler fire protection systems – GreenSprink

The GreenSprink Joint Laboratory aims to promote the development of an innovative automatic fire protection system for buildings based on water spray (using sprinklers) whose piping is under negative relative pressure (vacuum) at idle state. The « vacuum » technology has been patented by the company VACTEC, and displays numerous advantages compared to traditional systems. The absence of water in the piping (at idle state) allows the use of the system in areas exposed to frost, allowing to reduce by several degrees the temperature set point in the buildings where the system is installed, constituting a tremendous potential of energy savings. Moreover, its low water consumption makes the technology suited for developing and warm countries where fire protection systems should be adapted to the scarce ressources in drinkable water. However, because of the negative relative pressure in the pipes, the principle of vacuum sprinkler system is fundamentally different than that of the traditional systems, and involves complex physical phenomena (turbulent air/water flow, choked flow conditions at the sprinkler head…). In this context, VACTEC has called upon the scientific expertise of the PRISME laboratory (INSA Centre Val de Loire – Campus de Bourges) at numerous occasions, ie. internship of an engineering school student (2015), several service provisions, and a Centre Val de Loire research project (2015-2018). Hence, the GreenSprink aims to initiate a long term parternship between PRISME and VACTEC. The scientific objectives in this prospect include the development of a code considering the totality of the parameters involved in the fire protection of a building equipped with vacuum sprinkler systems, ie (i) fire detection ; (ii) transient two-phase (air/water) flow within the pipes subsequently to the opening of one/several sprinklers and activation of the main fire pump; (iii) the suppression of the fire, taking into account the interaction between the water spray from the sprinkler(s) and the fire. Numerical tools, including computational fluid dynamics (CFD) software, such as open source code OpenFOAM with solver FireFOAM will be employed for the modelling of the physical phenomena, and the coupling of the different steps involved will be carried out trough C++ or Matlab programming. The traditional systems (pipes filled with water or pressurized air at idle state) will also be modelled in order to underline the advantages of the vacuum sprinkler system, notably in terms of time necessary for suppression of the fire. Moreover, tests will be carried out both in the scale 1 laboratory of VACTEC, and on the experimental fire plateform VESTA of the PRISME Laboratory in order to enhance the understanding of the physical phenomena involved and to validate the numerical tool. From an industry point of view, the code developed in the context of the GreenSprink Joint Laboratory will be used for the conception and dimensioning stage of vacuum sprinkler systems of tree, gridded, and mesh design. Furthermore, the planned simulations and experiments aim to optimize the different elements constituting the vacuum system, such as the vacuum regulating unit, the electronic pressure variation detector, as well as the sprinkler head for use under vacuum conditions. These tasks will allow to develop new scientific approaches which can then be used as technical arguments for the promotion of the innovative vacuum sprinkler technology, which was certified by the industry insurance company FMGLOBAL (USA) since 2017. Thus, the strategy of the GreenSprink Joint Laboratory relies on the synergy between the academic and industry actor to provide answers to the following innovation targets:
• By 2 years: obtain an operational design code to support the commercialization of the vacuum sprinkler technology
• By 3 years: optimize the components of the vacuum sprinkler system
• By 5 to 7 years: extend the vacuum technology to other fire protection systems