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Modern control strategies for district-level heating and cooling supply systems pose a difficult challenge. In order to integrate a wide range of hot and cold sources, these new systems will rely heavily on accumulation and much lower operating temperatures. This means that predictive models advising the control strategy must take into account long-lasting thermal effects but must not be computationally too expensive, because the control would not be possible in practice. This paper presents a simple but powerful systematic approach to reducing the complexity of individual components of such models. It makes it possible to combine human engineering intuition with machine learning and arrive at comprehensive and accurate models. As an example, a simple steady-state heat loss of buried pipes is extended with dynamics observed in a much more complex model. The results show that the process converges quickly toward reasonable solutions. The new auto-generated model performs 5 × 104 times faster than its complex equivalent while preserving essentially the same accuracy. This approach has great potential to enhance the development of fast predictive models not just for district heating. Only open-source software was used, while OpenModelica, Python, and FEniCS were predominantly used.
Libor Kudela; Radomír Chýlek; Jiří Pospíšil. Efficient Integration of Machine Learning into District Heating Predictive Models. Energies 2020, 13, 6381 .
AMA StyleLibor Kudela, Radomír Chýlek, Jiří Pospíšil. Efficient Integration of Machine Learning into District Heating Predictive Models. Energies. 2020; 13 (23):6381.
Chicago/Turabian StyleLibor Kudela; Radomír Chýlek; Jiří Pospíšil. 2020. "Efficient Integration of Machine Learning into District Heating Predictive Models." Energies 13, no. 23: 6381.
Radomír Chýlek; Libor Kudela; Jiří Pospíšil; Ladislav Šnajdárek. Fine particle emission during fused deposition modelling and thermogravimetric analysis for various filaments. Journal of Cleaner Production 2019, 237, 1 .
AMA StyleRadomír Chýlek, Libor Kudela, Jiří Pospíšil, Ladislav Šnajdárek. Fine particle emission during fused deposition modelling and thermogravimetric analysis for various filaments. Journal of Cleaner Production. 2019; 237 ():1.
Chicago/Turabian StyleRadomír Chýlek; Libor Kudela; Jiří Pospíšil; Ladislav Šnajdárek. 2019. "Fine particle emission during fused deposition modelling and thermogravimetric analysis for various filaments." Journal of Cleaner Production 237, no. : 1.
This paper compares approaches for accurate numerical modeling of transients in the pipe element of district heating systems. The distribution grid itself affects the heat flow dynamics of a district heating network, which subsequently governs the heat delays and entire efficiency of the distribution. For an efficient control of the network, a control system must be able to predict how “temperature waves” move through the network. This prediction must be sufficiently accurate for real-time computations of operational parameters. Future control systems may also benefit from the accumulation capabilities of pipes. In this article, the key physical phenomena affecting the transients in pipes were identified, and an efficient numerical model of aboveground district heating pipe with heat accumulation was developed. The model used analytical methods for the evaluation of source terms. Physics of heat transfer in the pipe shells was captured by one-dimensional finite element method that is based on the steady-state solution. Simple advection scheme was used for discretization of the fluid region. Method of lines and time integration was used for marching. The complexity of simulated physical phenomena was highly flexible and allowed to trade accuracy for computational time. In comparison with the very finely discretized model, highly comparable transients were obtained even for the thick accumulation wall.
Libor Kudela; Radomir Chylek; Jiri Pospisil. Performant and Simple Numerical Modeling of District Heating Pipes with Heat Accumulation. Energies 2019, 12, 633 .
AMA StyleLibor Kudela, Radomir Chylek, Jiri Pospisil. Performant and Simple Numerical Modeling of District Heating Pipes with Heat Accumulation. Energies. 2019; 12 (4):633.
Chicago/Turabian StyleLibor Kudela; Radomir Chylek; Jiri Pospisil. 2019. "Performant and Simple Numerical Modeling of District Heating Pipes with Heat Accumulation." Energies 12, no. 4: 633.
The Ranque–Hilsch vortex tube represents a device for both cooling and heating applications. It uses compressed gas as drive medium. The temperature separation is affected by fluid flow behaviour inside the tube. It has not been sufficiently examined in detail yet and has the potential for further investigation. The aim of this paper is to compare results of numerical simulations of the vortex tube with obtained experimental data. The numerical study was using computational fluid dynamics (CFD), namely computational code STAR-CCM+. For the numerical study, a three-dimensional geometry model, and various turbulence physics models were used. For the validation of carried out calculations, an experimental device of the vortex tube of identical geometrical and operating conditions was created and tested. The numerical simulation results have been obtained for five different turbulence models, namely Standard k-ε, Realizable k-ε, Standard k-ω, SST k-ω and Reynolds stress model (RSM), were compared with experimental results. The most important evaluation factor was the temperature field in the vortex tube. All named models of turbulence were able to predict the general flow behaviour in the vortex tube with satisfactory precision. Standard k-ε turbulence model predicted temperature distribution in the best accordance with the obtained experimental data.
Radomír Chýlek; Ladislav Šnajdárek; Jirí Pospíšil. Vortex Tube: A Comparison of Experimental and CFD Analysis Featuring Different RANS Models. MATEC Web of Conferences 2018, 168, 02012 .
AMA StyleRadomír Chýlek, Ladislav Šnajdárek, Jirí Pospíšil. Vortex Tube: A Comparison of Experimental and CFD Analysis Featuring Different RANS Models. MATEC Web of Conferences. 2018; 168 ():02012.
Chicago/Turabian StyleRadomír Chýlek; Ladislav Šnajdárek; Jirí Pospíšil. 2018. "Vortex Tube: A Comparison of Experimental and CFD Analysis Featuring Different RANS Models." MATEC Web of Conferences 168, no. : 02012.