Ewch i’r prif gynnwys

Jose Hector Bastida Hernandez

Myfyriwr ymchwil, Yr Ysgol Peirianneg

Mae'r cynnwys hwn ar gael yn Saesneg yn unig.

Trosolwg

Ymchil

Traethawd ymchwil

Modelling and Control of District Heating and Cooling Systems

District heating and cooling systems (DHCS) provide thermal energy to a wide range of users. The efficient performance of DHCSs is critical for the reliability of the generation, supply and consumption of energy processes. Moreover, improvement of the energy management within DHCSs helps to tackle the greenhouse gas emission issue. Therefore, accurate models to analyse the thermal and hydraulic behaviours presented in a DHCS become essential to enhance the energy efficiency of the heating and cooling processes. Previous studies rely on steady-state models, in which the transient responses and their influence on the whole system are often ignored. The results and conclusions derived from these studies are based on assumptions that neglect critical dynamics under operating conditions changes. Moreover, some studies only consider the dispatch energy ignoring how it is transported, transferred and consumed. Thus, the fundamental variables that describe DHCS's behaviours have not been dynamically modelled in detail.


To bridge this research gap, one-dimensional hydraulic and thermal dynamic modelling approaches capable of providing a detailed understanding of the different underlying physics phenomena is presented in this thesis.  The prediction of the dynamic behaviour of fundamental variables such as temperature, pressure and mass flow rate through mathematical models allows analysing different operating scenarios. The well-described heat transfer process in the heat and cold supply processes is one of the key properties of the proposed approaches. For the hydraulic side, linear momentum and Newton's second law of motion are used to describe the pressure and fluid velocities of the DHCS's pipe network, considering critical parameters such as friction factor and loss coefficients of valves and pipes. Thus, modelling approaches are employed to develop  non-linear one-dimensional (1-D) models of the essential DHCS's components: pipe network, heat exchangers, thermal energy storages and buildings. The dynamic models' high-fidelity is based on the physic principles and the dynamic change of thermophysical properties of the fluids and materials involved in the energy supply process. Following this, phase change materials' enthalpy-specific heat relation is analysed to obtain accurate dynamic models of latent thermal energy storage.

Goruchwyliaeth

Carlos Ugalde

Dr Carlos Ugalde-Loo

Lecturer - Teaching and Research

alt

Dr Meysam Qadrdan

Lecturer - Teaching and Research

alt

Dr Muditha Abeysekera

Research Assistant

Cyhoeddiadau

2021

2019