This paper first introduces the concept of “exergy”, which quantifies what is consumed by any working systems from man-made systems such as heat engines to biological systems including human body. “Exergy” balance equation for a system can be derived by c
This paper summarises the work of the LowEx co-operation /1/. The aim was to promote rational use ofenergy by encouraging the use of low temperature heating systems and high temperature cooling systems ofbuildings. These systems can use a variety of fuels and renewable energy sources. Energy is used efficientlywhile providing a comfortable indoor climate. Exergy defines the quality of energy and is a concept fordesigning and assessing different heating and cooling systems. Application of exergy analysis into buildingshas not been common before.
This paper outlines the applicability of the “exergy” concept to describe the built environment for a better futuristic view of heating and cooling systems to be developed. We briefly review the fundamental laws of thermodynamics aiming at the derivation
The aim of this work is to observe the flow reversal that can appear at the time of interaction of hot and cold boundary layers in transient mixed convection in a vertical pipe.The instationary character of the flow is due to the application at the entry of the tube of a positive or negative temperature step. The transient mixed convection has a significant contribution in many industrial applications such as the air conditioning systems, the heat exchangers, nuclear plants, etc.
The contribution deals with the research on temperature fields in rooms heated in differentways at heating-up as well as in steady state conditions. The investigations are being carried out byphysical modelling with the use of interferometry, numerical modelling as well as measuring real rooms by thermocouples. The results show that interferometric research of two-dimensional temperature fields can be used for modelling in smaller heated rooms, in cars and various air-conditioned boxes. Numerical modelling seems to be more effective and can be used in wider range of application.
In January 2002, a new European project named HOPE (Health Optimization Protocol forEnergy-efficient Buildings) started with 14 participants from nine European countries. Thefinal goal of the project is to provide the means to increase the number of energy-efficientbuildings, i.e. buildings that are at the same time healthy and low energy users. Reducingenergy use by buildings also reduces CO2 emissions from primary energy used for ventilation,heating and humidity control.
The main aim of a heating system is to provide the objective thermal comfort parameters. The subjective thermal sensation of users is a very important aspect.The paper presents the results of experimental measurements on thermal comfort of indoorenvironment. The investigation was carried out in two blocks of flats. They were alike, but forthe installed thermal valves.
In highly insulated residential buildings, complying with the Passive House Standard, the space heat demand can be covered by air heating at air flow rates given by air quality requirements, without the need for additional air re-circulation or for a water heating system. The air distribution system is kept compact. In a common concept the supply air terminal is located above the door to the corridor. Such configurations were evaluated for typical air transfer devices and extreme supply temperatures.
The set points of supervisory control strategy are optimized with respect to energy use and thermal comfort for existing HVAC systems. The set point values of zone temperatures, supply duct static pressure, and supply air temperature are the problem variables, while energy use and thermal comfort are the objective functions. The HVAC system model includes all the individual component models developed and validated against the monitored data of an existing VAV system.
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