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A mathematical model has been developed, simulating various aspects of an iron blast furnace, for the purpose of analysing its behaviour. This involved the simulation of a counter current compressible gas flow, through a packed bed, dealing with the momentum and thermal energy of both phases. Directional resistances were added to the gas momentum, so as to account for the interphase friction caused by the packed bed. This enabled the prediction of the cohesive zone geometry, together with the active coke and stack, thus providing an important step for a successful analysis. The availability of multi-phase codes to solve such a system was limited and those existing being inadequate to represent these kinds of problems. What resulted was, the development of an algorithm to solve for two phases (gas and solids) with interspersed counter current flow, where the solids behaved as a packed bed. The algorithm developed is an enhanced version of existing algorithms. As well as the numerical model, a physical model of the raceway was developed, using dry ice particles to simulate the packed bed. The sublimation properties of the ice give a more realistic simulation to coke combustion, compared to the use of inert particles. The results of the experiment brought to light the effects of particle-particle interaction as being most significant in enabling the solids bed to move freely, around and into the raceway. From numerical modelling results, it is concluded that the ore:coke charging profile plays a dominant role in furnace behaviour. More interestingly, the gas distribution was not affected by raceway geometries when the cohesive zone was not in the immediate vicinity. It was therefore concluded that, the size and shape of the raceway zone has little influence on the gas distribution in the iron blast furnace.

An investigation of indoor thermal environment has been carried out by computational fluid dynamics approach. The study focuses on the thermal comfort evaluation, particularly the flow and heat transfer effects due to conjugate natural convection, furniture arrangement and occupant number, and flow oscillations. Key physical features of thermo-fluid such as velocity and temperature distributions, thermal sensation maps, and oscillation frequency and its energy are quantified, analysed and compared. The benchmark case study of airflow and heat transfer showed that ANSYS Fluent RNG k - 5 turbulence model with temperature boundary condition on the heated boundary calculated the bestresults, compared with available data. It also showed that air velocity increased along the boundary walls and especially hot wall which led flow direction upwards. At the centre of the flow circulation, air momentum is very weak (e.g. almost zero velocity magnitude). The increase of complex features (6. g. a box with/without heat) in the domain would lead to flow separations causing recirculations above the box and in the rear space of the domain and swirls in the front space presenting three-dimensional flow, and a thermal plume, compared with a two-dimensional clockwise flow in an empty room. The flow recirculations and thermal buoyancy enhanced velocity magnitude and turbulence level in the domain. In fact, the highest frequency was obtained in the room with an unheated box, followed by the room with a heated box. The forrhation of thermal plume from the heated box stabilised the flow in the upper part and the sides of the heated box on a spanwise plane. The frequency of velocity oscillation was consistent with temperature at the location although the energy of the fluctuation is much higher in temperature. Moreover the dominant frequency depended on the orientation of the flow circulation, for example a high energy at a lower frequency on a spanwise plane while a low energy at a higher frequency on a streamwise plane. In an empty room, it was found that there is no direct relation in an empty room (case 3.2.1) between velocity and turbulent flow in power spectral density and frequency, and each of time-history velocity oscillations is independent and random. At the mid- height of the domain, the energy of the velocity fluctuation is relatively weak. The results from the study of conjugate natural convection heat transfer in a ventilated room with localised heat source and window glazing showed that the size of heat source and window glazing, the wall thickness and wall material property are important factors to temperature change and heat loss. For example, 30 % of wall thickness reduction caused 35 % more of heat loss through the wall and 9 % of comfort temperature. From the study of furniture arrangement and occupant number in a 3-D model room with localised heat source and window glazing, it was found that the presence of furniture induced flow recirculation and higher velocity around furniture and the presence of thermal occupant formed thermal plume in the fluid domain, increasing volume-averaged temperature by maximum 15 %, compared with that of unoccupied and empty model room. Increase in the number of occupants and thermal furniture helped increase air temperature by 6.5 %, compared with that of single occupant and the averaged PPD (Predicted Percentage of Dissatisfied) value around the occupants by maximum 5.4 % for one occupant and 11.5 % for two occupants, respectively. The location of occupant was very sensitive to flow stream path, e. g. the PPD distribution was symmetrical in the spanwise position but became asymmetrical in streamwise position. Further investigation of thermal comfort level using Fanger’s indices due to ventilation rate and thermal load led that desirable indoor environment might be achieved with higher ventilation flow rate (Uinlet > 0.7 m/s) rather than reducing heat generation from the heating sources for more occupants introduced to the room. The results in the thesis summarise some of the important reservations with regard to the CFD capability and reliability for indoor thermal environment and present data would be useful for the built environment thermal engineers in design and optimisation of domestic rooms.

In this study, it is aimed to develop an innovative thermochemical energy storage system through material, reactor and process based investigations for building space heating applications. The developed system could be integrated with solar thermal collectors, photovoltaic panels or heat pumps to store any excess energy in the form of heat for later use. Thereby, it is proposed to address the problem of high operational costs and CO2 emissions released by currently used fossil fuel based heating systems in buildings. The aim of the study has been achieved by investigating and evaluating five of the following aspects: • Investigation of the feasibility of building integrated solar driven THS system under cold and mild climates, • Synthesis, characterization and physical experimentation of novel composite sorption energy storage materials • Development and investigation of a modular laboratory scale sorption reactor that use embedded air diffusers inside the sorbent for improving the energy storage density • Development and investigation of a full- scale modular solar driven THS system • Development and investigation of a heat pump driven sorption storage heater using multi-layer fixed bed sorption reactor These works have been assessed by means of computer simulation, laboratory and field experimental work and have been demonstrated adequately. The key findings from the study confirm the potential of the examined technology. Initially, a comprehensive review on thermal energy storage, with the aim of investigating the latest advancements on THS systems was performed. A comparative analysis on applicability of different heat storage methods for short term and seasonal heat storage under climate conditions in the UK, was also carried out. Results showed that short term heat storage is not a feasible option in the UK due to the very limited solar radiation. For the case of seasonal heat storage, it was found that, each 1 m3 of THS can provide averagely 14% of monthly (October to March) heating demand of a 106 m2 building, whereas LHS and SHS can provide 6% and 2% respectively. Later on, a range of candidate composite sorption materials were synthesized and characterized. Based on the applied characterization techniques, it was found that Vermicuilite-CaCl2 (SIM-3a) has excellent Ed coupled with good EMC and temc with its TGA analysis also suggesting significant mass loss in the working range 30 < T < 140 °C. Physical experimentation of the developed materials in a small scale custom test rig was also performed and in accordance with the characterization results, SIM-3a displayed the best hygrothermal and cyclic performance. These findings suggested that SIM-3a has very good potential for use in an open THS system. Upon completion of the material based studies, a 3kWh laboratory scale novel reactor using perforated pipes embedded inside the heat storage material was developed. The overall energy density of the reactor using SIM-3a was found 290 kWh/m3. Based on the obtained encouraging results, same concept was up scaled to a modular 25 kWh sorption pipe heat storage and similar energy density was achieved. Following the experimental work, theoretical analysis of the THS potential in Mediterranean climate conditions is conducted with a case study of the Island of Cyprus. The analysis results showed that the required heat storage volume to fully compensate heating demand of a domestic building in winter (December to February) is 5.25 m3 whilst the time required for charging the THS material with 8 m2 solar air collectors is slightly more than a month. The economic and environmental analyses results showed that payback period of the solar driven THS is 6 years whilst total CO2 emissions savings over 25 years lifetime is 47.9 tonnes. In order to validate the applicability of THS in Cyprus, a small prototype of integrated sorption pipe-solar concentrator was also developed and tested for room heating. It was found that adsorbent could be regenerated with solar energy during winter day time to be utilized at night for space heating. Study results also showed that sorption pipe with a heat storage volume of 0.017 m3 could meet up to 87% of the daily heat demand of a 12.4 m2 building. In order to validate the performance of the laboratory tested THS material and concept, a real scale (1000 kWh) modular solar driven THS system was developed based on the interpretation of the obtained theoretical, numerical and experimental data in earlier stages of the study. The preliminary testing on the prototype showed that each of four reactors could discharge a total of 248 kWh of thermal energy with an average thermal power of 4.8 kW. Additionally it is found that, in direct solar heating mode, transpired solar collectors used in the system could also generate daily total of 17 kWh thermal energy for the average solar intensity of 0.3 kW/m2. In the final stage of the study, a heat pump driven sorption storage heater was developed and investigated. The developed system performance was assessed with 5 different adsorption materials and under different operating conditions. The study results showed that Sim-3a and Vermiculite–(LiCl-CaCl2) (Sim-3cl) has the best hygrothermal performances and hygro-cyclic efficiencies. According to study results, COPs varies in the range of 1→2 depending on sorption materials properties and system operating conditions.

Enhancing the heat output of the hydronic central heating system in buildings can play a major role in reducing energy consumption and CO2 emission. The main aim of this PhD research is to investigate the effect of pulsed flow input on the energy consumption of panel radiators in hydronic central heating systems and the user indoor comfort defined by ASHRAE standard 55 and EN ISO 7730. The research covers thermal performance of panel radiator and the indoor comfort. The work was performed using dynamic control modelling, CFD and experimental testing to prove the concept. Results from the mathematical and CFD modelling of the hydronic radiator with pulsed flow using various frequencies and amplitudes showed that 20% to 27% of energy saving can be achieved compared to the constant flow while maintaining the same radiator target surface temperature of 50oC as recommended by the BS EN442. The indoor comfort results were also achieved as recommended by international standards including CO2 concentration at 1000PPM±50PPM, relative humidity at 50±9%, comfort temperature at 20±1.6oC, air velocity of below 0.15m/s and draught risk parameters of less than 15%. The numerical results agreed well with experimental results with maximum deviation of radiator temperature output of ±4.1%, indoor temperature ±2.83% and energy saving of ±1.7%. The energy saved due to the pulsed flow is attributed to the enhancement of the radiator heat transfer performance that leads to higher heat output at lower average mass flow rate of the hot water.

The buoyancy-driven air flow and the associated energy transfer within a half-scale stairwell model have been investigated experimentally and theoretically. The experimental work comprised the larger part of the investigation. The stairwell model consisted of a lower and an upper compartment connected through the stairway. The recirculation of air was maintained by a continuous supply of heat in the lower compartment. Two different cases, referred to as closed and open non-sloping ceiling stairwells, were considered. In the former, the stairwell formed a closed system, and in the latter situation the air was allowed to enter and leave the stairwell through small openings in the lower and upper compartments, a situation which may arise in practice due to the presence of cracks. The experimental work provided detailed measurements of the velocity and temperature within the stairwell model. Hot-wire anemometers of a temperature-compensated type were used to measure the velocities, and the air temperatures were measured using platinum resistance probes. These measurements, supported by flow visualisation using smoke, provided a detailed description of the flow field. Due to the symmetry condition which existed in the stairwell, the measurements were carried out in only one-half of the stairwell. The results for both closed and open cases include the velocity and temperature profiles at the throat area (minimum area between the stairway and the lower compartment ceiling) for various distances from the side wall, mean temperatures in the upper and the lower compartments, volume and mass flows up and down the stairwell. The effect of the heat input rate on these parameters is also included. The results also include the heat losses through various surfaces bounding the system, heat and mass transfer through the stairwell joints and inlet and outlet openings, and the wall temperatures. The theoretical work was concerned with a numerical prediction of turbulent flow in two-dimensions. The k-c turbulence model, with the buoyancy terms included, was adopted. The governing equations for mass, momentum, energy and those of the turbulence model were solved using a finite-volume method. The model incorporates the SIMPLE algorithm for the derivation of pressure. The wall-function method was used for the treatment of the flow near the walls. The hybrid discretisation scheme was adopted. The predicted f low pattern was in good agreement with the pattern established by experiment. The proportion of the heat loss from the upper compartment was also in good agreement with the experiment. The maximum velocities in the throat area were underpredicted. The discrepancy between the prediction and experiment is believed to arise from shortcomings of the turbulence model, the treatment of the near-wall flow and the two-dimensionality of the numerical model.

No description available.

This work deals with a "passive flow monitoring" technique which can be used to help determine the energy used by a building's heating system. The thesis first highlights the background and importance of energy monitoring in buildings. This work points out that energy monitoring is an important feature in the running of buildings today. In the past, the energy crisis in the 1970's made people aware of how important it was to have knowledge of how buildings consume energy. More recently, environmental issues have reinforced the importance of gaining good quality information on energy use in buildings. This thesis investigates the use of combined port flow characteristics/control signal relationships for three port control valves to predict system water flow rate in heating systems. A laboratory test rig was built and a range of three port valves were tested. A series of combined port flow characteristics/control signal relationships were developed from measurements from the test rig. Curve fit models were then applied to these relationships in the form of polynomial equations. Where practical relationships could not be measured for a valve, a theoretical valve model was derived. In order to validate the polynomial regression model and the mathematical model, the test rig was modified to take into account practical heating system characteristics. A series of flow characteristic results were produced from the modified test rig so that the performance of the two models (empirical and mathematical) could be evaluated. It was found that the empirical model performed well in predicting combined port flow ratios with RMS errors ranging between 2.73% and 6.54%. The mathematical model gave overall prediction errors between -2.63% and +9.25% which compare favourably with the performance of some flow meters. The work then goes on to present an energy use algorithm which incorporates the valve model (empirical or theoretical) for use in BEMS.

No description available.