


Politecnico di Torino  
Academic Year 2015/16  
01OAHQD, 01OAHNE Numerical design of thermal systems 

Master of sciencelevel of the Bologna process in Mechanical Engineering  Torino 





Subject fundamentals
The subject aims to present and discuss some advanced topics in the field of engineering thermodynamics and heat transfer. Both theoretical and applied aspects are considered. In particular, modeling and numerical methods are presented and applied to relevant systems in engineering thermodynamics. This course is designed to broaden the student’s background required for the analysis and design of real systems and devices involving fluid flow and heat transfer phenomena.

Expected learning outcomes
The student is expected to know physical, technical and design aspects of some typical energy systems. Additionally the course provides to the student the basic knowledge to deal with design aspects of fluid distribution networks and steam generators. Another objective is to convey to the student the ability to understand the complex phenomena related to radiative heat transfer.
Furthermore the student is expected to know the numerical techniques necessary to model fluid distribution network. Similarly the student is also expected to learn the ability to implement numerical models that describe radiative heat transfer in engineering systems, and to become familiar with the theory and the numerical models commonly used to calculate the energy demand of a building and the energy provided by the heating system and equipment. 
Prerequisites / Assumed knowledge
The prerequisites for this subject are the subjects on thermodynamics and heat transfer, chemistry, and advanced engineering thermodynamics.

Contents
Generality:
The subject is structured on theoretical lessons and practical applications. In particular, a district heating system (users + pipe network + thermal plant) is considered as the application of the numerical methods that are introduced. The first part of the subject is focused on fluid distribution networks. On the basis of conservation equations introduced in previous courses fluid distribution networks are theoretically characterized. Computational techniques are introduced to numerically solve the fluid dynamic and thermal problems typical of a fluid distribution network. Then the student is required to apply the methods illustrated during the lectures to a district heating network. Afterwards, the topics related to the energy demand calculation of a building and its equipment are provided and some relevant energy savings measures are discussed. The theory outlined in this section is at the basis of the numerical methods commonly used to calculate the primary energy demand of a building. In the last part of the subject , convection and radiation heat transfer are considered. Radiation exchange between gray bodies and radiative behavior of participating media, such as gases, are presented. The zonal model is presented as numerical technique to solve radiative heat transfer problems involved in engineering systems. An application of the zonal model to a steam generator is proposed. In such analysis both convective and radiative heat transfer are numerically modeled in order to compute the temperature field in the system and the radiative heat transfer rate. Topics: Introduction to the subject. Introduction to numerical techniques and its relevance in the field of the field of engineering thermodynamics. Introduction to networks. Numerical models for the analysis of fluid distribution networks. Constrains, objectives, type of problem and methodologies involved in the analysis of typical real networks. Graph theory and monodimensional models of complex systems. Topological model, branch and node concept. Definition of graph, tree, cotree, cutset and loop. Incidence matrix an major topological correlations. Physical models and conservation equations. The steadystate fluid dynamic problem for a fluid distribution network. Linear method and nodal method. Building energy balance. Climatic data analysis. Thermal load and energy demand calculation that accounts for transmission, ventilation, internal and solar gains. Heating system equipments and related efficiencies. Energy savings measures. Comfort, IAQ. Introduction to radiative heat transfer: geometrical definitions, emitted radiation, incident radiation, interaction between radiation and matter. Black and gray body concepts. Radiative heat transfer between black surfaces. Radiative exchange between gray surfaces. Net radiative heat flux. Introduction to zonal model and radiative heat transfer in a cavity of grey surfaces. Total interchange areas and adiabatic surfaces. Radiative heat transfer in the presence of a participating media. Gassurface and surfacesurface radiative exchange. Real gas model and direct flux surfaces. Energy balances 
Delivery modes
During an application to a district heating system is proposed to the students. The application is composed of four parts, each corresponding to the application of a numerical method to a portion of the system.
The first part concerns the design of a district heating network. The problem consists in the choice of pipe diameters and the evaluation of mass flow rates and pressure drops along the network. In addition two different network designs are investigated. The following part is related to the evaluation of the energy demand for space heating of a building of the district heating network, in a couple of casesstudy: base case and refurbishment aimed to energy savings. The following issues are addressed: heating load and energy demand calculation, building time constant and indoor temperature management, calculation of the heating system efficiencies. The last sections concern the design of the thermal plant. First, the size of cogeneration system and that of the additional boilers are selected. Then the analysis of a steam generator is performed. A numerical model is developed to study the combustion process and the heat transfer phenomenon taking place in the system. Specifically the zonal model is used to model radiative heat transfer in the combustion chamber considering the interaction between radiation and combustion products. 
Texts, readings, handouts and other learning resources
Notes of the lectures available online on the "Portale della Didattica".
Text books: A. Bejan, "Advanced Engineering Thermodynamic" John Wiley & Sons 1997. F.P. Incropera, D.P. DeWitt, Fundamentals of Heat and Mass Transfer, John Wiley & Sons, 2002. H.C. Hottel, A. F. Sarofim. "Radiative Transfer" McGraw – Hill, Inc. 1967. M. F. Modest, "Radiative heat transfer" Academic Press 2003. R. Siegel, J.R. Howell, "Thermal radiation heat transfer". CRC Press, 1992. 
Assessment and grading criteria
The exam is in the oral form and it is based on the theoretical aspects and the proposed application.
A written report is requested for the proposed applications. 
