O objetivo deste trabalho foi desenvolver um sistema para atender as necessidades de controle e automação de um sistema de climatização para abrigos de equipamentos eletrônico, contemplando o controle dos níveis de umidade, de temperatura e a eliminação de partículas de poeira suspensa no ar. Existe uma ampla gama de tipos de abrigos, como subestações pré-fabricadas, data-centers, shelters de telecomunicação, salas elétricas, dentre outros. Ao abrigar equipamentos elétricos em funcionamento, a quantidade e acumulo de energia térmica no interior do ambiente onde se localizam ocasiona a elevação da temperatura a níveis inaceitáveis ao bom funcionamento dos equipamentos abrigados. Além disso, a umidade e a existência de particulados no ambiente podem causar a deterioração dos componentes eletrônicos. Por esse motivo é inevitável a utilização de um sistema de climatização para proteção desses equipamentos. O ato de refrigerar, desumidificar, purificar e renovar o ar permite o aumento da vida útil dos equipamentos instalados no interior desses abrigos. O projeto desenvolvido neste trabalho para automatização de um sistema de climatização foi aplicado a uma subestação elétrica pré-fabricada para uma indústria do ramo de mineração.Inicialmente realizou-se um estudo das exigências que o sistema de climatização teria que atender. Realizou-se uma modelagem do sistema levando-se em conta os requisitos do projeto e, para que o sistema fosse aplicado em campo, a lógica de programação foi testada em fábrica por meio do software de programação do CLP e posteriormente comissionado antes da entrega final em campo. O teste de campo consistiu em ligar o sistema automatizado de climatização e simular todo o funcionamento e condições de falhas possíveis, certificando que as respostas do sistema estivessem dentro das especificações definidas durante o projeto. O sistema desenvolvido encontra-se em funcionamento e serve de modelo para o desenvolvimento de novos projetos de climatização. / The aim of this study was to develop a system to attend the needs of automation and control of a cooling system for electronic equipment shelters, including the control of humidity, temperature and elimination of dust particles suspended in air. There is a wide range of types of shelters, such as prefabricated substations, data centers, telecom shelters, electrical rooms, among others. In house electrical equipment in operation, the amount and accumulation of heat inside this type o shelters where they are located causes the temperature rise to unacceptable levels for the proper functioning of equipment housed. Moreover, the presence of moisture and particulates in the environment may cause deterioration of electronic components and so it is inevitable to use a cooling system for protection of such equipment. The act of cooling, dehumidify, purify and renew the air permit to increase the lifetime of the equipment installed inside these shelters. The project developed in this work for automation of a cooling system was applied to an electrical substation for a prefab industry mining sector. Initially we carried out a study of the requirements that the HVAC system and would have to attend before the system was applied in the field, the programming logic was tested at the factory through the PLC programming software and subsequently commissioned before final delivery in field. The field test was to connect the automated climate control and simulate the entire operation and fault conditions possible, ensuring that the system responses were within the specifications established during the project. The system is designed for operation and serves as a model for the development of new draft cooling.

ABE, V.C. Determinação de parâmetros de operação de sistema de distribuição de ar frio pelo piso em ambientes de escritórios. 2007. 132 p. Dissertação (Mestrado) - Departamento de Engenharia de Construção Civil da Escola Politécnica da Universidade de São Paulo, São Paulo, 2007. Atualmente, um dos principais requisitos para que um ambiente de escritório atenda plenamente às necessidades de uso e ocupação é a flexibilidade, mas com conforto. O sistema de distribuição de ar frio pelo piso (Underfloor Air Distribution System - UFAD) está sendo utilizado nos edifícios de escritórios para garantir a flexibilização integrada do sistema com o mobiliário. Trata-se de um sistema que fornece ar frio proveniente de um plenum, através de difusores localizados nos painéis do piso elevado. Os difusores de ar podem ser ajustados, ou reposicionados pelos próprios usuários dos ambientes, possibilitando o controle das condições térmicas no entorno próximo, de acordo com suas preferências individuais. Embora o sistema de distribuição de ar pelo piso apresente diversas vantagens com relação ao sistema de distribuição de ar convencional, ainda há falta de informações objetivas e diretrizes de projeto padronizadas, havendo a necessidade de realização de mais pesquisas na área. A introdução da Dinâmica dos Fluidos Computacional (Computational Fluid Dynamics - CFD) apresentou uma alternativa para as pesquisas experimentais relacionadas ao estudo do escoamento do ar. Assim, para o desenvolvimento do presente estudo foram utilizados recursos de dinâmica dos fluidos computacional, com o uso do código FLUENT. O objetivo do presente trabalho é apresentar uma estratégia para a determinação dos parâmetros de operação de sistemas de distribuição de ar pelo piso aplicados a ambientes de escritórios. A estratégia baseiase no estabelecimento de inter-relações entre os principais parâmetros que definem o escoamento do ar em ambientes com o sistema de distribuição de ar pelo piso: a vazão de ar insuflado, a temperatura do ar insuflado e a diferença de pressão entre o plenum pressurizado e o interior do ambiente. O emprego da estratégia possibilita que o projetista identifique as diversas combinações entre os parâmetros de operação que resultem numa mesma condição desejada, permitindo assim a escolha da opção mais satisfatória. / ABE, V.C. Determination of operation parameters of rooms with underfloor air distribution system. 2007. 132 p. Dissertation (Master Course) - Departamento de Engenharia de Construção Civil da Escola Politécnica da Universidade de São Paulo, São Paulo, 2007. Nowadays, one of the main requirements of an office room to fully attend the use and occupation needs is the flexibility, but with comfort. The underfloor air distribution system is being used in the office buildings to guarantee the integrated flexibility of the system with the furniture layout. The system supplies cooled air to the room from a pressurized plenum, passing through air diffusers located in the raised floor panels. The air diffusers can be adjusted or relocated by the room users themselves, making possible the control of the thermal conditions in their surroundings, according to their individual preferences. Though the underfloor air distribution system presents a lot of advantages with regard to conventional overhead distribution systems, there is still a lack of objective information and standardized guidelines, and the necessity of accomplishment of more researches about the subject. The introduction of Computational Fluid Dynamics presented an alternative for the experimental tests related to the study of airflow in rooms. Thus, for the development of the present study a CFD tool was used, the code FLUENT. The purpose of the present work is to develop a strategy for the determination of the operation parameters of an underfloor air distribution system applied to office rooms. The strategy is based on the establishment of interrelations between the main parameters that define the airflow in rooms with the underfloor air distribution system: the input volume flux, the input air temperature and the pressure difference between underfloor plenum and the room. The use of this strategy enables the designer to identify several combinations of the operation parameters that result in one desired condition, allowing the choice of the most satisfactory option.

The HVAC system configuration is a conceptual design of the HVAC system, including the employed components, the topology of the airflow network, and the control strategy with set points. Selection of HVAC system configuration is normally done in the early stage of the design process. The configuration design, however, has significant impacts on the performance of the final system. This thesis describes the development of the design synthesis of optimal HVAC system configurations by Evolutionary Algorithm. In this research, the HVAC system configuration design synthesis has been formulated as an optimisation problem, in which, the component set of the configuration, the topology of the airflow network, and the control set points for the assumed supervisory control strategy, are the optimisation variables. Psychrometrics-based configuration model has been developed in order to evaluate the optimisation objective of minimising the annual energy consumption of the HVAC system. The optimisation is also subjected to a number of design constraints, including the connectivity of the topology, the performance limitations of the components, and the design requirements for the air-conditioned zones. The configuration synthesis problem is a multi-level optimisation problem. The topology depends on the set of selected components, whereas the search space of the control set points changes with the different components and topology. On the other hand, the performance of the configuration is assessed with its optimum operation; therefore the control set points have to be optimised for each configuration solution, before the optimum configuration can be identified. In this research, a simultaneous evolutionary approach has been developed. All optimisation variables of the configuration have been enwded into an integrated genotypic data structure. Evolutionary operators have also been developed to search the topological space (for the optimum topology) and parametric space (for the optimal control set points) at the same time. The performance of the developed approach has been validated with example optimisation problems. It is concluded that the implemented evolutionary algorithm has been able to find (near) optimum solutions for various design problems, though multiple trials may be required. The limitations of this approach and the direction of future development have been discussed.

This research is related to the control of energy consumption and efficiency in building Heating Ventilation and Air Conditioning (HVAC) systems and is primarily concerned with controlling the function of heating. The main goal of this thesis is to develop a control system that can achieve the following two main control functions: a) detection of unexpected indoor conditions that may result in unnecessary power consumption and b) energy efficiency control regarding optimal balancing of two parameters: the required energy consumption for heating, versus thermal comfort of the occupants. Methods of both orientations were developed in a multi-zone space composed of nine zones where each zone is equipped with a wireless node consisting of temperature and occupancy sensors while all the scattered nodes together form a wireless sensor network (WSN). The main methods of both control functions utilize the potential of the deterministic subspace identification (SID) predictive model which provides the predicted temperature of the zones. In the main method for detecting unexpected situations that can directly affect the thermal condition of the indoor space and cause energy consumption (abnormal situations), the predictive temperature from the SID model is compared with the real temperature and thus possible temperature deviations that indicate unexpected situations are detected. The method successfully detects two situations: the high infiltration gain due to unexpected cold air intake from the external surroundings through potential unforeseen openings (windows, exterior doors, opened ceilings etc) as well as the high heat gain due to onset of fire. With the support of the statistical algorithm for abrupt change detection, Cumulative Sum (CUSUM), the detection of temperature deviations is accomplished with accuracy in a very short time. The CUSUM algorithm is first evaluated at an initial approach to detect power diversions due to the above situations caused by the aforementioned exogenous factors. The predicted temperature of the zone from the SID model utilized appropriately also by the main method of the second control function for energy efficiency control. The time needed for the temperature of a zone to reach the thermal comfort zone threshold from a low initial value is measured by the predicted temperature evolution, and this measurement bases the logic of a control criterion for applying proactive heating to the unoccupied zones or not. Additional key points for the control criterion of the method is the occupation time of the zones as well as the remaining time of the occupants in the occupied zones. Two scenarios are examined: the first scenario with two adjacent zones where the one is occupied and the other is not, and the second scenario with a multi-zone space where the occupants are moving through the zones in a cascade mode. Gama and Pareto probability distributions modeled the occupation times of the two-zone scenario while exponential distribution modeled the cascade scenario as the least favorable case. The mobility of the occupants modeled with a semi-Markov process and the method provides satisfactory and reasonable results. At an initial approach the proactive heating of the zones is evaluated with specific algorithms that handle appropriately the occupation time into the zones.

Please read the abstract in the section 00front of this document / Thesis (PhD (Mechanical Engineering))--University of Pretoria, 2007. / Mechanical and Aeronautical Engineering / unrestricted

Buildings contribute a significant part to the electricity demand profile and peak demand for the electrical utilities. The addition of renewable energy generation adds additional variability and uncertainty to the power system. Demand side management in the buildings can help improve the demand profile for the utilities by shifting some of the demand from peak to off-peak times. Heating, ventilation and air-conditioning contribute around 45% to the overall demand of a building. This research studies two strategies for reducing the peak as well as shifting some demand from peak to off-peak periods in commercial buildings: 1. Use of gas heat pumps in place of electric heat pumps, and 2. Shifting demand for air conditioning from peak to off-peak by thermal energy storage in chilled water and ice. The first part of this study evaluates the field performance of gas engine-driven heat pumps (GEHP) tested in a commercial building in Florida. Four GEHP units of 8 Tons of Refrigeration (TR) capacity each providing air-conditioning to seven thermal zones in a commercial building, were instrumented for measuring their performance. The operation of these GEHPs was recorded for ten months, analyzed and compared with prior results reported in the literature. The instantaneous COPunit of these systems varied from 0.1 to 1.4 during typical summer week operation. The COP was low because the gas engines for the heat pumps were being used for loads that were much lower than design capacity which resulted in much lower efficiencies than expected. The performance of equivalent electric heat pump was simulated from a building energy model developed to mimic the measured building loads. An economic comparison of GEHPs and conventional electrical heat pumps was done based on the measured and simulated results. The average performance of the GEHP units was estimated to lie between those of EER-9.2 and EER-11.8 systems. The performance of GEHP systems suffers due to lower efficiency at part load operation. The study highlighted the need for optimum system sizing for GEHP/HVAC systems to meet the building load to obtain better performance in buildings. The second part of this study focusses on using chilled water or ice as thermal energy storage for shifting the air conditioning load from peak to off-peak in a commercial building. Thermal energy storage can play a very important role in providing demand-side management for diversifying the utility demand from buildings. Model of a large commercial office building is developed with thermal storage for cooling for peak power shifting. Three variations of the model were developed and analyzed for their performance with 1) ice storage, 2) chilled water storage with mixed storage tank and 3) chilled water storage with stratified tank, using EnergyPlus 8.5 software developed by the US Department of Energy. Operation strategy with tactical control to incorporate peak power schedule was developed using energy management system (EMS). The modeled HVAC system was optimized for minimum cost with the optimal storage capacity and chiller size using JEPlus. Based on the simulation, an optimal storage capacity of 40-45 GJ was estimated for the large office building model along with 40% smaller chiller capacity resulting in higher chiller part-load performance. Additionally, the auxiliary system like pump and condenser were also optimized to smaller capacities and thus resulting in less power demand during operation. The overall annual saving potential was found in the range of 7-10% for cooling electricity use resulting in 10-17% reduction in costs to the consumer. A possible annual peak shifting of 25-78% was found from the simulation results after comparing with the reference models. Adopting TES in commercial buildings and achieving 25% peak shifting could result in a reduction in peak summer demand of 1398 MW in Tampa.

Please read the abstract in the section 00front of this document / Dissertation (MEng (Electrical Engineering))--University of Pretoria, 2006. / Electrical, Electronic and Computer Engineering / unrestricted

An investigation into an appropriate urban design response to the development of the Gautrain Rapid Rail Link station in the Pretoria CBD, which acts as a catalyst for urban renewal and social development. Focus is aimed at the technical resolution according to the climatic conditions. / Dissertation (MArch (Prof))--University of Pretoria, 2006. / Architecture / unrestricted

Studies concluded that more that 10% of all energy consumed in the world is expended by building air-conditioning systems. Energy efficiency in building and HVAC (Heating, Ventilating and Air-conditioning) design is therefore exceptionally important. A cost¬-effective way to improve the energy efficiency of a HV AC system, without compromising indoor comfort, is by implementing better control. System energy cost savings of up to 50% can be realised by optimising the system operating control strategies with direct payback periods of less than a year. However, when changing the operating strategy of a system it is often difficult to predict the resulting changes in system energy consumption and indoor comfort. To achieve these predictions, a dynamic simulation tool, which can efficiently and accurately simulate the building with the HV AC and control system in an integrated fashion, is required. Extensions to the integrated tool QUICKcontrol is therefore proposed to suite the needs of the energy service contractor. QUICKcontrol still has many shortcomings in the availability of component models for certain equipment commonly used in building systems today. New dynamic component models were therefore derived in this study. The accuracy and applicability of integrated building and natural ventilation modelling is illustrated in animal housing facilities. The predicted results obtained during this study were satisfactory to use these models with confidence in this type of building applications. The applicability of building, HV AC system and control simulations was illustrated in conference facilities. The results obtained show the value of integrated building and system simulation in the evaluation of energy cost saving inventions in commercial buildings. The mining and industrial sectors in South Africa consume about 40% of ESKOM's total electrical energy production. Mines alone use nearly 20% of the electricity provided by ESKOM. Ventilation and cooling (VC) systems are responsible for approximately 25% or R750 million of this energy. It will therefore be beneficial if the mines can be more energy clever in order to reduce their VC operating costs. The use of an extended integrated building and system simulation tool was therefore realised to investigate the potential for energy cost savings in mine VC applications. To extend QUICKcontrol for the simulation of other large thermal systems found in mining and industrial applications, new component models and simulations procedures were developed. Two case studies were performed with the extended tool to illustrate its applicability in thermal systems other than building systems. The potential for Demand Side Management (DSM) on a surface cooling plant and an underground clear water-pumping system was investigated. Satisfactory results were obtained during the two investigations to utilise this extended tool with confidence in practice. With more extensions to the tool it should be possible to investigate the potential for energy cost saving on any other thermal industrial applications. / Thesis (PhD (Mechanical Engineering))--University of Pretoria, 2007. / Mechanical and Aeronautical Engineering / unrestricted

The need for efficient, sustainable, and planned utilization of resources is ever more critical. In the U.S. alone, buildings consume 34.8 Quadrillion (1015) BTU of energy annually at a cost of $1.4 Trillion. Of this energy 58% is utilized for heating and air conditioning. Several building energy analysis tools have been developed to assess energy demands and lifecycle energy costs in buildings. Such analyses are also essential for an efficient HVAC design that overcomes the pitfalls of an under/over-designed system. DOE-2 is among the most widely known full building energy analysis models. It also constitutes the simulation engine of other prominent software such as eQUEST, EnergyPro, PowerDOE. Therefore, it is essential that DOE-2 energy simulations be characterized by high accuracy. Infiltration is an uncontrolled process through which outside air leaks into a building. Studies have estimated infiltration to account for up to 50% of a building’s energy demand. This, considered alongside the annual cost of buildings energy consumption, reveals the costs of air infiltration. It also stresses the need that prominent building energy simulation engines accurately account for its impact. In this research the relative accuracy of current air infiltration calculation methods is evaluated against an intricate Multiphysics Hygrothermal CFD building envelope analysis. The full-scale CFD analysis is based on a meticulous representation of cracking in building envelopes and on real-life conditions. The research found that even the most advanced current infiltration methods, including in DOE-2, are at up to 96.13% relative error versus CFD analysis. An Enhanced Model for Combined Heat and Air Infiltration Simulation was developed. The model resulted in 91.6% improvement in relative accuracy over current models. It reduces error versus CFD analysis to less than 4.5% while requiring less than 1% of the time required for such a complex hygrothermal analysis. The algorithm used in our model was demonstrated to be easy to integrate into DOE-2 and other engines as a standalone method for evaluating infiltration heat loads. This will vastly increase the accuracy of such simulation engines while maintaining their speed and ease of use characteristics that make them very widely used in building design.