The ventilation system is in itself a huge necessity in our everyday life as it provides sufficient amount of fresh air to our indoor climate, while it simultaneously circulates the residing air pollutants out of the building. Although, for this to be made possible, large amounts of energy is required to be consumed, which in turn leads to an increased energy cost. The knowledge to minimize the use of energy occurs in many different scopes of practices throughout our society. Many people however, avoid such measures due to the high initial costs which are presented, but also because they haven't enough awareness of how they should rectify the problem. The Study is mainly based on researching previously performed measures of system upgrades in the ventilation industry regarding ventilation systems with heat recovery, while understanding the different elements that influences the choice to either upgrade or renovate the already existing system. The implementation of thesis happened through information gathering, a literature study and a qualitative research, which in this case were interviews. The literature study consisted of scientific reports, evaluations and a couple of digital sources which were relevant to the subject we were focusing on. The interviews on the other hand were conducted with experienced officials and employees in the ventilation industry, with the purpose of having a better understanding behind the reason of a system being upgraded. The final results of the study indicated that the most common reason why a costumer/property owner sought an upgrade or renovation of the ventilation system was mainly because of contamination in the heat exchanger, which in return increased the energy consumption while at the same time impaired the indoor climate. / Ventilationssystemet är en nödvändighet i vår vardag, då det ska tillföra god inomhusluft samtidigt som den cirkulerar bort luftföroreningarna som finns inuti byggnaden. Men för att detta ska möjliggöras förbrukas stora mängder energi, som i sin tur leder till en ökad energikostnad. Kunskapen för att minimera energianvändningen förekommer i många varierande verksamhetsområden. Däremot är det många som undviker sådana åtgärder på grund av de höga initialkostnaderna men även eftersom de inte har kännedom kring hur dom ska åtgärda problemet. Studien är främst baserad på att ta reda på tidigare utförda åtgärder av systemuppgradering i ventilationsbranschen med inriktning inom ventilationssystem med värmeåtervinning, och genom det begripa vilka faktorer som påverkar valet till att man vill uppgradera eller renovera sitt befintliga system. Genomförandet av arbetet grundades på faktainsamling, litteraturstudie och en kvalitativ forskning i form av intervjuer. Den inhämtade litteraturen bestod av vetenskapliga rapporter, teknikupphandlingar, utvärderingar och digitala källor som var relevanta kring ämnesområdet. Intervjuerna utfördes med erfarna tjänstemän inom branschen, i syfte med att innehava en djupare förståelse kring systemuppgradering av ventilationssystem och anledningen till detta. Slutresultat av undersökningen tydde på att den mest förekommande anledningen till att en kund/fastighetsägare sökte en uppgradering eller renovering av sitt ventilationssystem med värmeåtervinning var på grund av nedsmutsning i värmeväxlaren, vilket försämrade inomhusklimatet och ökade energiförbrukningen.

Computational Fluid Dynamics (CFD) has emerged as an indispensable tool in various engineering fields, particularly in the design and optimization of HVAC systems in complex environments, such as engine rooms. This paper presents a comprehensive overview of CFD applications and focuses on the engine rooms of the Grange Castle Power Plant in Dublin, Ireland. Sustainable Development Capital LLP (SDCL) is constructing a state-of-the-art power plant at Grange Castle Business Park in Dublin, featuring six MAN 18V51/60DF engine generators and a total net export capacity of 111 MW. The plant uses pioneering dualfuel technology and serves as a contingency facility to stabilize the power grid amidst increasing integration of renewable energy. It functions as a responsive backup power generator and a peak load reducer, aiding the Irish government's goal of sourcing 80% of power from renewables by 2030. The initiative is part of a wider strategy including MAN Energy Solutions and Greener Ideas Limited, contributing to three new power plants in Ireland with a combined capacity of 311 MW.This study utilizes steady-state CFD simulations, employing the widely adopted k-epsilon turbulence model. Known for its robustness and computational efficiency, the k-epsilon turbulence model is utilized to analyse one engine cell at the Grange Castle Power Plant. As a two-equation model, it involves solving two additional transport equations alongside the Navier-Stokes equations to simulate fluid flow.Commonly applied in engineering applications, this model will be utilized to provide predictions of airflow and temperatures within the cell during standby and running states over the course of the year. By leveraging the strengths of the k-epsilon turbulence model, the study seeks to gain valuable insights into the complex fluid dynamics within the engine cell, ultimately helping to optimize its performance and efficiency. The analysis focused on one engine cell, with the setup and geometry for each cell being identical.Specifically, the research investigates maintaining the temperature within the cell, temperature distributions, airflow comparisons to design specifications and requirements, heating load and adequate airflow calculations, and potential benefits of optimizing the design and operation of the engine cell.The dimensions and characteristics of the engine room, along with the engines themselves and the heat they generate, play a significant role in the design process. In this study, there are several essential factors to consider, including a negative pressure ventilation system, as well as combustion and cooling air provided through air intake units that draw air from outside the engine hall and exhaust it using fans mounted on the roof. The ventilation system must be designed to maintain the room temperature within the range of 9 °C to 45°C at different points in the room. Since the engine combustion air will be drawn from inside the engine hall, the ventilation system must provide the required volumes of combustion air at all times, along with the necessary ventilation. The CFD analysis conducted in this study provides the groundwork for designing an effective ventilation system that can maintain optimal temperature conditions in the engine room. Using the simulation results, the ventilation system will be optimized to ensure the required temperature is maintained while also preventing the formation of explosive atmospheres.iiAlso, the simulation study presented in this report showcases the ability of CFD simulations to predict airflow and temperature fields in the engine room of a power plant. It is essential to understand the different scenarios' conditions to design a reliable and efficient engine room system. Furthermore, CFD simulations have proven to be an effective tool for optimizing HVAC installations to meet specific building requirements even before installing any equipment. CFD takes into account all factors influencing airflow and temperature, ensuring finely tuned designs even in confined spaces.To accurately analyse and simulate the environment, a 3D model of the engine and room is created using Inventor and AutoCAD software. However, for complex systems like the engine room, simplifying the geometry is necessary when preparing a CFD model. This is because including every detail can result in an excessive number of mesh elements, leading to longer simulation times and higher computational costs. Therefore, striking a balance between geometric complexity and computational efficiency is important for an optimal CFD model. By creating a simplified model, the CFD simulation can be more computationally efficient while still accurately capturing important flow features. The 3D model allows for seamless integration with the CFD software, enabling accurate representation of the environment for analysis.The study conducted simulations for a high-power diesel & gas engine room under four different scenarios, covering various seasonal and load conditions. The results indicated that a heating coil with a 250 kW capacity is required to preheat the airflow of 25.5 m³/s by 8 °C to maintain the required temperature above 9 °C during winter. Similarly, during summer, fans with an airflow rate of 60 m³/s are necessary to keep the engine room temperature below 45 °C. This analysis is critical for designing an optimal ventilation system in engine rooms, ensuring sufficient airflow and maintaining appropriate engine temperature to prevent engine start failure. The simulation results provide invaluable information for HVAC engineers to design an efficient and reliable engine room system.Through the utilization of CFD simulations, engineers can simulate and analyse the performance of the HVAC system under various conditions, providing them with the necessary information to make well-informed decisions to ensure that the system meets the required performance criteria. Implementing CFD in the early stages of HVAC design provides valuable insights, saving engineers time and money associated with real-life testing and validation. By leveraging CFD simulations, engineers can virtually test and evaluate multiple design alternatives, ventilation strategies, and system configurations prior to actual implementation. This proactive approach helps engineers pinpoint potential issues, optimize system design for enhanced efficiency and effectiveness, and minimize the need for expensive post-installation modifications and adjustments.

Ground-coupled ventilation (GCV) is a system that exchanges heat with the soil. Because ground temperatures are relatively higher during the cold season and lower during the hot season, the system takes advantage of this natural phenomenon. This research focused on designing a ground-coupled ventilation system evaluation tool of many factors that affect system performance. The tool predicts the performance of GCV system design based on the GCV system design parameters including the location of the system, pipe length, pipe depth, pipe diameter, soil type, number of pipes, volume flow rate, and bypass system. The tool uses regression equations created from many GCV system design simulation data using Autodesk Computational Fluid Dynamics software. As a result, this tool helps users choose the most suitable GCV system design by comparing multiple GCV systems' design performances and allows them to save time, money, and effort. / Doctor of Philosophy / Ground-coupled ventilation (GCV) is a system that exchanges heat with the soil. Because ground temperatures are relatively higher during the cold season and lower during the hot season, the system takes advantage of this natural phenomenon. This research focused on designing a ground-coupled ventilation system evaluation tool of many factors that affect system performance. The tool predicts the performance of GCV system design based on the GCV system design parameters including the location of the system, pipe length, pipe depth, pipe diameter, soil type, number of pipes, volume flow rate, and bypass system. The tool uses equations created from many GCV system designs’ simulation data using simulation software. As a result, this tool helps users choose the most suitable GCV system design by comparing multiple GCV system designs’ performance and allows them to save time, money, and effort.

As pessoas estão cada vez mais viajando de avião e, muitas vezes, em viagens longas. A qualidade do ar torna-se uma questão crucial. Uma forma de melhorar a qualidade do ar e as condições de conforto térmico dentro de uma cabine de aeronave está na utilização de novos sistemas de ventilação personalizada. O objetivo do presente trabalho consiste na análise experimental da influência de um sistema de ventilação personalizada (PV) na concentração, dispersão e remoção de partículas expiratórias em cabine de aeronave com sistema por mistura (MV) e por deslocamento (DV). Os ensaios foram realizados em um mock-up de cabine de aeronave comercial de 12 assentos, com 4 assentos por fileira. O ar foi insuflado na cabine a 18°C pelo sistema MV ou DV, correspondendo a uma leve sensação de frio, e a 24°C pelo sistema personalizado (PV), com vazão de 3,0 l/s, operando no assento próximo à fuselagem e ao corredor, alternadamente. As partículas simulando uma pessoa espirrando foram injetadas em dois pontos no fundo da cabine, respectivamente, no assento próximo à fuselagem e naquele junto do corredor, a 1,10m do piso, que corresponde à região de respiração. Foram medidas velocidades e temperaturas do ar e de partículas ao longo de toda a cabine. Os resultados mostraram que no sistema MV o sistema PV somente influenciou o escoamento do ar e a concentração de partículas no assento onde o sistema PV estava operando, com uma eficiência na remoção de partículas de até 30%. No sistema DV, por sua vez, o sistema PV apresentou eficiência de remoção de até 49% nos assentos em que estava operando. Contudo, o sistema PV pode aumentar em até 32% a concentração de partículas no assento próximo da janela quando o sistema PV estava operando no assento próximo do corredor, no sistema DV. Finalmente, os resultados mostraram resultados mais promissores do sistema PV no sistema MV, com melhoria significativa na remoção de partículas nos assentos onde está operando, sem influenciar negativamente no assento ao lado. / People are increasingly traveling by plane and often on long journeys. Air quality becomes a crucial issue. One way to improve air quality and thermal comfort conditions within an aircraft cabin is to use new personalized ventilation systems. The objective of the present work is the experimental analysis of the influence of a personalized ventilation system (PV) on the concentration, dispersion and removal of expiratory particles in aircraft cabin with mixed system (MV) and displacement (DV). The tests were performed in a 12 seat commercial aircraft cabin mock-up, with 4 seats per row. The air was inflated in the cabin at 18 ° C by the MV or DV system, corresponding to a slight cold sensation, and at 24 ° C by the custom system (PV), with a flow rate of 3.0 l / s, operating in the nearby seat the fuselage and the aisle, alternately. Particles simulating a person sneezing were injected at two points in the bottom of the cockpit, respectively, in the seat near the fuselage and next to the corridor, 1.10m from the floor, which corresponds to the breathing region. Air and particle velocities and temperatures were measured throughout the cabin. The results showed that in the MV system the PV system only influenced the air flow and the concentration of particles in the seat where the PV system was operating, with a particle removal efficiency of up to 30%. The DV system together with PV system showed removal efficiency of up to 49% in the seats in which it was operating. However, the PV system can increase particle concentration in the near-window seat by up to 32% when the PV system was operating on the seat next to the aisle in the DV system. Finally, the results showed more promising results of the PV system in the MV system, with significant improvement in particle removal in the seats where it is operating, without negatively influencing the next seat.

Main purpose of project is design of economical ventilation system. Designed preasure equal air heating system is supportet by sollar collectors and fluid-ground heat exchanger.

The diploma thesis is consisting of theoretic part, which deal with used ventilating systems, ways of waste heat recovery and describe basic types of air-conditioning systems. Following part attend to design of ventilating system and multi-split air-conditioning system for flat. Part of design of ventilation system is calculation of noise levels in rooms. Air-conditioner design is based on calculation of thermal stress. Annual demand of cold and heat demand are calculated using TRANSYS software. Design documentation is part of the diploma thesis.

The diploma thesis is consisting of theoretic part, which deals with used ventilating systems, describes basic types of air-conditioning systems and basic characteristics and diversification of radiant cooling systems. Following part attend to design of ventilating system and radiant cooling system for cooling of the flat. Design of the ventilation systém is based on minimum air flow per person. Design of the radiant cooling system is based on calculation of thermal loads. Design documentation is part of the diploma thesis as well as the calculations made in excel.

A disseminação de agentes infecciosos em ambientes interiores é um assunto de interesse da sociedade em geral e uma questão de saúde pública, tendo em vista os surtos recentes do vírus SARS, gripe suína, gripe aviária, etc. Em particular, o sistema com suprimento de ar individualizado têm se mostrado eficaz, atuando como barreira contra contaminação cruzada entre ocupantes. Diversas metodologias têm sido aplicadas nesses estudos, tal como gás traçador, geradores de partículas e simulação CFD, muitas vezes sem muito critério, ou com equipamentos e simulações excessivamente complexas. Neste contexto, o objetivo do presente trabalho é desenvolver um processo robusto e com menor complexidade do que os utilizados atualmente para avaliar a dispersão de contaminantes aéreos em ambientes interiores. O processo desenvolvido é aplicado em um estudo de caso onde a influência de um sistema de ventilação personalizado de cabine de aeronave é avaliado sobre a ótica da infecção cruzada. O trabalho contempla a realização de atividades de simulação computacional (CFD) e medições experimentais no ambiente interno de uma cabine de avião (mock-up), onde os campos de velocidade do ar são medidos com Velocimetria por Imagem de Partículas (PIV), partículas entre 2 e 10m são geradas com um gerador de aerossol e contadas com contadores ópticos portáteis. Obteve-se boa correlação entre os resultados numéricos e experimentais para o campo de velocidades e boa concordância qualitativa entre as contagens de partículas no experimento e nas simulações CFD Lagrangeanas. Observou-se, dentre outros aspectos, que a válvula gasper, tal como ensaiada no presente trabalho, contribui para a qualidade do ar na zona de respiração dos ocupantes sentados, promovendo um aumento nas taxas de deposição de partículas nas superfícies internas do mock-up. / The indoor dispersion of infections agents still concern the society, and has become a matter of public health, taken into account the outbreak of SARS in 2003, and the recent cases of influenza strains (H1N1, avian flu, SARS, etc). The use of personalized ventilation has improved the occupants\' air quality on recent evaluations, working as a contaminant spread barrier. Different kinds of methodologies are usually applied for those studies, such as tracer gas, particle generators and CFD simulations, sometimes without adequate criteria, or applying quite complex equipment and simulation methodologies such as transient analysis. Therefore, the main objective of the present work is to develop a robust method, and if possible less complicated than the current ones, to evaluate the dispersion of indoor airborne contaminants. Moreover, one\'s intend to apply the proposed method in a case study to evaluate the influence of a personalized ventilation system to the spread of indoor air contaminants. The study is composed by CFD simulations and experimental measurements inside an aircraft cabin mock-up, where the velocity and temperature field, as well as particle concentration are measured. Particle Image Velocimetry technique is used to analyse air flow velocities. Particles from 2 to 10µm are produced with aerosol generator and injected into the cabine. Finally, particle distributions are measured with hand held optical counters to evaluate air quality at the breathing zone. Good correlation between numerical and experimental results was obtained for velocity field, and adequate qualitative agreement was obtained for concentration field. One\'s conclude the investigated personalized ventilation system has improved the air quality around occupants breathing zone, mainly by increasing the deposition rates at the internal cabin surfaces.

A disseminação de agentes infecciosos em ambientes interiores é um assunto de interesse da sociedade em geral e uma questão de saúde pública, tendo em vista os surtos recentes do vírus SARS, gripe suína, gripe aviária, etc. Em particular, o sistema com suprimento de ar individualizado têm se mostrado eficaz, atuando como barreira contra contaminação cruzada entre ocupantes. Diversas metodologias têm sido aplicadas nesses estudos, tal como gás traçador, geradores de partículas e simulação CFD, muitas vezes sem muito critério, ou com equipamentos e simulações excessivamente complexas. Neste contexto, o objetivo do presente trabalho é desenvolver um processo robusto e com menor complexidade do que os utilizados atualmente para avaliar a dispersão de contaminantes aéreos em ambientes interiores. O processo desenvolvido é aplicado em um estudo de caso onde a influência de um sistema de ventilação personalizado de cabine de aeronave é avaliado sobre a ótica da infecção cruzada. O trabalho contempla a realização de atividades de simulação computacional (CFD) e medições experimentais no ambiente interno de uma cabine de avião (mock-up), onde os campos de velocidade do ar são medidos com Velocimetria por Imagem de Partículas (PIV), partículas entre 2 e 10m são geradas com um gerador de aerossol e contadas com contadores ópticos portáteis. Obteve-se boa correlação entre os resultados numéricos e experimentais para o campo de velocidades e boa concordância qualitativa entre as contagens de partículas no experimento e nas simulações CFD Lagrangeanas. Observou-se, dentre outros aspectos, que a válvula gasper, tal como ensaiada no presente trabalho, contribui para a qualidade do ar na zona de respiração dos ocupantes sentados, promovendo um aumento nas taxas de deposição de partículas nas superfícies internas do mock-up. / The indoor dispersion of infections agents still concern the society, and has become a matter of public health, taken into account the outbreak of SARS in 2003, and the recent cases of influenza strains (H1N1, avian flu, SARS, etc). The use of personalized ventilation has improved the occupants\' air quality on recent evaluations, working as a contaminant spread barrier. Different kinds of methodologies are usually applied for those studies, such as tracer gas, particle generators and CFD simulations, sometimes without adequate criteria, or applying quite complex equipment and simulation methodologies such as transient analysis. Therefore, the main objective of the present work is to develop a robust method, and if possible less complicated than the current ones, to evaluate the dispersion of indoor airborne contaminants. Moreover, one\'s intend to apply the proposed method in a case study to evaluate the influence of a personalized ventilation system to the spread of indoor air contaminants. The study is composed by CFD simulations and experimental measurements inside an aircraft cabin mock-up, where the velocity and temperature field, as well as particle concentration are measured. Particle Image Velocimetry technique is used to analyse air flow velocities. Particles from 2 to 10µm are produced with aerosol generator and injected into the cabine. Finally, particle distributions are measured with hand held optical counters to evaluate air quality at the breathing zone. Good correlation between numerical and experimental results was obtained for velocity field, and adequate qualitative agreement was obtained for concentration field. One\'s conclude the investigated personalized ventilation system has improved the air quality around occupants breathing zone, mainly by increasing the deposition rates at the internal cabin surfaces.

Regarding the great importance of a good working environment, in this research, ventilation systems installed in kitchens of restaurants were studied in order to avoid problems and to understand the key factors that can influence on the performance of the system. The results obtained were taken into account to provide some recommendations to a real ventilation system of a restaurant called Pastaria in Gävle (Sweden). This concrete ventilation system was not performing good, and some calculations based on the kitchen design were made trying to offset the problem. A large number of scientific studies related to restaurant kitchen hoods and ventilation systems were used to get the findings. These articles were obtained from scholar web databases. The main problem found in kitchen hoods is the inadequate exhaust airflow. The minimum required airflow varies depending on the size and shape of the hood. Keil et al. (2004) found in their research that only 39% and 24% of the studied hoods met the minimum recommended airflow from ACGIH and ASHRAE guidelines, respectively. Other key factors found are related to the kitchen design. The kitchen hood is recommended to have incorporated a capture hood covering all the burners. Side panels can be employed to increase the capture and containment. High efficiency filters and rigid ducts are also recommended. The cleaning of the ventilation ducts is also an important factor, they are recommended to be cleaned between 1 to 9 years depending on the activity of the kitchen. Thus, key factors such as disturbing airflows and the presence/movement of the cooks can disturb the kitchen hood performance. A very effective solution, isolating the fumes below the hood, that is getting developed is the installation of an inclined air curtain from the cooking surface. Related to the kitchen hood and the ventilation system of the Pastaria restaurant. Some measurements and information were obtained in a visit to the restaurant. After calculations, it was obtained based on the kitchen design that is required a minimum airflow of 4 140 m3/hour. In order to do that, the heat exchanger Swegon Silver C RX, installed in the system, requires a minimum size of 11/12. The distribution of the kitchen appliances in this restaurant seems to be correct. However, a future study in order to see if there are disturbing airflows affecting the kitchen hood performance must be carried out. If after checking all recommendations the performance of the kitchen hood is not good enough yet, an inclined air curtain may be installed due to their great effectiveness against problems of hoods. In conclusion, it was clearly obtained that a correct kitchen distribution design and calculations must be done for each restaurant in order to install the most adequate kitchen hood with the best characteristics. This way, fumes, odors, moisture and particles will be easily exhausted allowing a better environment out of risks to the establishment and customers health.