Master's thesis and Internship : Framework for Evaluating the Design Requirements of ATEX-Certified Psychrometric Chambers

Abstract

Driven by increasingly stringent environmental and safety regulations, as well as emerging restrictions on per- and polyfluoroalkyl substances (PFAS), the HVAC/R industry is rapidly transitioning toward natural refrigerants like highly flammable propane (R290). The use of such fluids in HVAC/R applications requires special testing facilities to safely evaluate their thermal performance.

This thesis addresses these risks by implementing a zone-avoidance engineering strategy. By combining safety ventilation that ensures sufficient dilution, with automated fail-safe shutdown sequences, potential refrigerant leaks are properly managed. This guarantees both personnel and installation safety. This approach enables the establishment of a Zone of Negligible Extent (Zone 2 NE), thereby eliminating the need for explosion-proof instrumentation within the experimental volume.

To operationalize this framework, a comprehensive engineering design tool was developed as a Python-based Streamlit web application. The application integrates a three-tier computational engine comprising a transient 1D thermal RC network wall model for multi-layer heat transfer, a dynamic energy balance module to evaluate real-time HVAC thermal load compensation, and a tree-based decision solver to map EN 378 compliance pathways and compute mandatory volumetric safety ventilation flow rates.

Finally, a techno-economic analysis was performed on a baseline twin-chamber configuration (32.19 m³ individual volume, 30 kW dynamic thermal load compensation). A budget offer from Aralab indicates a capital investment of €600,000 without accounting for installation costs, whereas a bottom-up cost estimation for a self-assembled alternative ranges from €58,587 to €100,453. While the in-house solution offers significant cost savings, it shifts a substantial engineering workload, safety validation and full legal liability onto the university.