Novel control of run-around heat recovery system: Evaluation of the novel control method’s performance through laboratory experiments
Publicerad
Författare
Typ
Examensarbete för masterexamen
Master's Thesis
Master's Thesis
Modellbyggare
Tidskriftstitel
ISSN
Volymtitel
Utgivare
Sammanfattning
Run-around coil (RAC) systems are particularly well-suited for applications requiring complete
separation between supply and exhaust airflows, such as hospitals, laboratories, and other
facilities with stringent hygiene or contamination control requirements. Unlike rotary or plate type heat exchangers, RAC systems ensure full airstream separation while offering design
flexibility and modular installation, making them appropriate for complex and specialized
ventilation scenarios. However, their efficient operation critically depends on the accurate
control of the circulating liquid flow rate to achieve optimal heat recovery performance.
Traditional control strategies regulate liquid flow based on balancing the heat capacity flow rates
of air and liquid media, which requires accurate real-time knowledge of their thermophysical
properties. This approach becomes challenging in dynamic operational environments, especially
under demand-controlled ventilation (DCV) conditions, where airflows fluctuate in response to
changing occupancy. Moreover, accurately measuring flow rates and properties in real-time
often increases system complexity, limiting the practicality of such control strategies.
To address these challenges, a novel temperature-based control method was developed and
evaluated through laboratory experiments. This new approach relies on temperature
measurements, rather than flow measurements or thermophysical property estimations, to
regulate the system. The method aims to enhance system adaptability, reduce measurement
uncertainties, and maintain stable heat recovery performance across a wide range of ventilation
demands and external conditions. The experimental evaluation focused on testing this strategy's
effectiveness, robustness, and responsiveness compared to conventional flow-based control
methods.
The results demonstrate that the temperature-based control method (Xt) offers a reliable and
efficient alternative, particularly in applications where fluid properties are variable or where
accurate flow sensors are impractical. With appropriate tuning of control parameters,
specifically the proportional and integral settings, the method achieved consistently high
effectiveness and system stability across variable conditions. The findings suggest strong
potential for integrating this novel control approach into both new and existing RAC
installations, supporting improved energy efficiency and simplified operation in real-world DCV
systems.
Beskrivning
Ämne/nyckelord
Run-around Coil (RAC), Heat Recovery, Temperature-Based Control, Demand-Controlled Ventilation (DCV), Energy Efficiency