Engineering Commons^™

Methodology To Compare Performance Of Residential Hvac Systems Operating In Cooling Mode, Manoj Bhandari

Mechanical Engineering Theses

Residential HVAC systems are selected and installed based on the goals of the customer. For spec homes, the most common types of systems are traditionally ducted with standard efficiency. However, for custom homes, the recent trend has included high-efficiency HVAC systems that are often accompanied by air-tight home envelopes with highly thermally resistant foam insulation in the walls. Several high-efficiency systems are available in the market with the performance of these systems varying between the different manufacturers and the types of systems. The systems available in the market can be compared and ranked based on their thermal performance and energy …

Spaspace Humidity Control Through A Single Speed Versus A Variable Speed Hvac Solution, Koukouni P. Kone

Mechanical Engineering Theses

Conventional air conditioning systems in houses respond to thermal loads by means of controlling dry-bulb temperature through the thermostat. As part of the process of conditioning the air, dehumidification is also provided. However, as houses are becoming more efficient, supplemental dehumidification is often necessary in homes located in hot and humid climates to control relative humidity intentionally. This study compared the dehumidification performance of three residential air conditioning systems: a system with a variable speed mode (VSPD), a system with an enhanced dehumidification mode activated (Enhanced Dehum), and a system without enhanced dehumidification capabilities (Normal Cooling). The research facility was …

Semi-Open Space And Micro-Environmental Control For Improving Thermal Comfort, Indoor Air Quality, And Building Energy Efficiency, Meng Kong

Dissertations - ALL

Local air delivery, heating, and cooling combined with local space partition and confinement (called semi-open space or SOS) have the potential to provide micro-environment that is tailored to the individual preference of the occupants, and hence increase the percentage of satisfied occupancy from currently 80% to near 100%. This research investigates the use of a micro-environmental control system (µX) and semi-open space (SOS) to efficiently provide the desired thermal comfort and air quality conditions for individual occupants while the ambient air temperature set-points were relaxed for reducing the overall energy consumption of the building. A computational fluid dynamics (CFD) model …

The Effects Of Exhaust Vent Location On Thermal Comfort Inside The Residential Buildings Equipped With An Evaporative Cooling System, Armin Saraei

UNLV Theses, Dissertations, Professional Papers, and Capstones

Inlet and outlet conditions, Including size and location, have significant effects on the air distribution, temperature, humidity and thermal comfort in the buildings. In the current study, various strategies are presented for exhaust air vents and the effects of inlet and outlet vents locations are evaluated on providing thermal comfort in the residential and industrial buildings. To provide thermal comfort, three key factors need to be investigated based on ASHRAE standard 55- 2013 as follows: Comfort Zone, Thermal Sensation and Draft Rate. Flow distribution is studied as well in order to investigate the strategies, which make more vorticity in the …

Evaluating The Performance Of Passive Chilled Beams With Respect To Energy Efficiency And Thermal Comfort, Janghyun Kim

Open Access Dissertations

Existing modeling approaches for passive chilled beams determined from tests on individual chilled beams in a laboratory are not adequate for assessing overall energy usage and occupant comfort within building simulation programs. In addition, design guidelines for passive chilled beam systems are needed for identifying appropriate applications and optimal configurations. This thesis includes (i) extensive experimental studies for characterizing the performance of passive chilled beams, in both laboratory settings and in field studies, (ii) development of passive chilled beam performance prediction models, (iii) integration of these models into building simulation models/tools and (iv) use of building simulation for overall assessment …

Optimal Design Of A Thermoelectric Cooling/Heating System For Car Seat Climate Control (Cscc), Abdulmunaem H. Elarusi

Masters Theses

In this work, optimal design of a thermoelectric device itself (element length, cross section area and number of thermoelements) applied in a car seat climate control (CSCC) is studied analytically using our newly developed optimization method. This method, which is based on the thermoelectric ideal equations along with dimensional analysis allows us to simultaneously obtain the best combination of the thermoelectric parameters in order to improve the performance of the thermoelectric device regarding the cooling/heating power and the coefficient of performance (COP). First, this method was implemented to investigate the optimal design of a readily existing air-to-air thermoelectric system. Then, …

Application And Analysis Of Asymmetrical Hot And Cold Stimuli, Ahmad Manasrah

USF Tampa Graduate Theses and Dissertations

The human body has a unique mechanism for perceiving surrounding temperatures. When an object is in contact with the skin, we do not feel its temperature. Instead, we feel the temperature change that is caused on our skin by that object. The faster the heat is transferred, the more intense the thermal sensation is. In this dissertation, a new dynamic thermal display method, where different rates of warm and cold are applied on the skin to generate a unique sensation, is presented. The new method can be related in a wide range of applications including thermal haptics and virtual reality. …

A Feasibility Study Of Model-Based Natural Ventilation Control In A Midrise Student Dormitory Building, Steven James Gross

Dissertations and Theses

Past research has shown that natural ventilation can be used to satisfy upwards of 98% of the yearly cooling demand when utilized in the appropriate climate zone. Yet widespread implementation of natural ventilation has been limited in practice. This delay in market adoption is mainly due to lack of effective and reliable control. Historically, control of natural ventilation was left to the occupant (i.e. they are responsible for opening and closing their windows) because occupants are more readily satisfied when given control of the indoor environment. This strategy has been shown to be effective during summer months, but can lead …

Analysis Of Human Thermal Comfort Using A Coupled Model For Predicting Human Body-Environment Heat And Mass Exchange, Ahmed M. Al-Mogbel

Mechanical & Aerospace Engineering Theses & Dissertations

Recent advances in computational fluid dynamics (CFD) make it possible to accurately predict many features of airflow within ventilated spaces. The present study investigates thermal comfort aspects of an occupant in a conditioned space, using a CFD code.

The heat and mass transfer between the human body and the surrounding environment is analyzed by a coupled model that accounts for dispersal of metabolically generated heat in the body to the surroundings by the combined mechanisms of radiation, convection, respiration and evaporation. A two-node model in which two coupled non-linear algebraic equations govern the skin temperature and the body core temperature …

Effects Of Ventilation On Human Thermal Comfort In Rooms, Ahmed F. Alfahaid

Mechanical & Aerospace Engineering Theses & Dissertations

Nowadays, the majority of people spend up to 90% of their time indoors; as a result, the maintenance of optimal indoor climate conditions has become important for their overall health and comfort. The main goal of this study is to predict numerically the flow and temperature patterns and the human thermal comfort conditions in an indoor environment using displacement ventilation.

A Computational Fluid Dynamics (CFD) code has been used to analyze thermal comfort conditions for a fullscale ventilated room. Unstructured grids have been used to discretize the numerical domain. Before undertaking a detailed investigation, the code was validated by comparing …