This thesis presents an approach for identifying critical model parameters in dynamic air-conditioning systems using limited sensor information. The expansion valve model and the compressor model parameters play a crucial role in the system model's accuracy. In the past, these parameters have been estimated using a mass flow meter; however, this is an expensive devise and at times, impractical. In response to these constraints, a novel method to estimate the unknown parameters of the expansion valve model and the compressor model is developed. A gray box model obtained by augmenting the expansion valve model, the evaporator model, and the compressor model is used. Two numerical search algorithms, nonlinear least squares and Simplex search, are used to estimate the parameters of the expansion valve model and the compressor model. This parameter estimation is done by minimizing the error between the model output and the experimental systems output. Results demonstrate that the nonlinear least squares algorithm was more robust for this estimation problem than the Simplex search algorithm. In this thesis, two types of expansion valves, the Electronic Expansion Valve and the Thermostatic Expansion Valve, are considered. The Electronic Expansion Valve model is a static model due to its dynamics being much faster than the systems dynamics; the Thermostatic expansion valve model, however, is a dynamic one. The parameter estimation algorithm developed is validated on two different experimental systems to confirm the practicality of its approach. Knowing the model parameters accurately can lead to a better model for control and fault detection applications. In addition to parameter estimation, this thesis also provides and validates a simple usable mathematical model for the Thermostatic expansion valve.

Master´s thesis is focused on measurement uncertainty problems, particularly on the uncertainty determination and then on the practical application. The thesis is divided into three parts. A theoretical part deals with issues concerning uncertainties on the theoretical level, transition from the measurement error to the measurement uncertainty. This part also clarifies the basic terms concerning this issues based on “ČSN ISO 5168” standard and another legislative materials. The other part is focused on temperature regulations by thermostatic heads and valves. This part also handles thermostatic heads and valves history, division, generally use and legislative background represented by standard „EN 215“. Practical part follows previous sections. I am determining the measure uncertainty of thermostatic heads and valves flow characteristic determining device. All the results and knowledge obtained are given in the conclusion of the thesis.

This study seeks to expand the range of climates and conditions in which free cooling from an economizer can replace air conditioning power consumption in residential applications. To explore this issue, we first discretize a simple building model in space and in time. We then solve the associated energy and mass balances for the estimated hourly heating and cooling loads and humidity conditions with respect to an annual climate profile. We propose a forecast-based algorithm to control the rate of outdoor airflow brought in by an economizer, in response to the upcoming cooling load to be experienced by the interior airspace. The algorithm takes advantage of a range of acceptable temperatures for thermal comfort by precooling the envelope overnight to delay the onset of cooling demand during the day. In order to consider the highest potential benefit from such an algorithm, we bypass the considerable problem of forecast accuracy by basing the inputs on the upcoming cooling load according to an initial simulation of the full year. On the whole, even with the forecast-based control, the results of the study have much in common with previous findings in the literature. Precooling works better to reduce cooling load in cases of higher thermal and moisture mass, but a humid climate severely restricts when free cooling is beneficial. For the example house considered here with the Austin climate and other assumptions, the effect of the proposed forecast-based economizer control was to greatly reduce the indoor air cooling load while greatly increasing the number of annual hours of unacceptably high indoor humidity. When we adjusted the forecast-based algorithm to avoid the excess humidity, the remaining reduction in cooling load was not significant. To investigate further how a forecast-based economizer could reduce cooling load in humid climates, the prinicipal task should be to extend the control algorithm to forecast and manage upcoming indoor humidity levels in the same fashion as was done in this study for indoor air temperature. / text

The automotive thermostat currently contributes significantly to the potential to reduce the output of the exhaust gases. The heart of the modern thermostat is the ball valve assembly which also deals with this master‘s thesis. First of all the principles of the quality of the automotive thermostat are described with the choice of further deeper examined properties. The manufacturing process of a ball element and PTFE sealing ring is described. Subsequently the problem of increased production of nonconforming products in production is studied focusing on the surface texture of teflon ring and shape analysis of the ball element. Finally a recommendation for practice with regard to the reduction of additional costs associated with poorly manufactured part is created and further action on this issue is recommended.

The object of this work is to propose innovative solutions on the assembly line in company Honeywell. Optimization of this line will be achieved by changing the concept of calibration. The current stabilization in air-conditioned chamber will be replaced by operational calibration incorporated in the assembly line, which will depend on ambient temperature. This work will be mainly contained a description of the current status, the proposed changes and economic evaluation.

This master's thesis is focused on the design of a device for testing the thermo-regulating properties of thermostatic heads. The engineering design, design of testing device has been composed according to the standard EN 215: Thermostatic radiator valves – Requirements and test methods. Based on these designs, sensors and regulation elements, which are suitable for testing, have been designed. Last part of the thesis deals with operating the device and measurement procedure.

[pt] O uso de nanofluidos na área de Termociências tem sido de grande interesse tendo em vista possibilitar uma melhora significativa na capacidade de transferência de calor em máquinas térmicas. Isto se deve em função da presença de partículas em suspensão com diâmetros menores que 100 nm que são dispersas em fluidos convencionais. Parâmetros como viscosidade e condutividade térmica são fatores determinantes no desempenho desses materiais como fluidos térmicos em diferentes aplicações. O presente trabalho teve como objetivo a realização de ensaios experimentais para determinação da viscosidade dinâmica e da tensão cisalhante de três nanofluidos com diferentes composições, sob condições de temperatura controlada (faixa de -10 graus Celsius a 30 graus Celsius). Dois parâmetros adicionais - taxa de cisalhamento e taxa de rotação - foram condicionantes nos ensaios. A montagem da bancada experimental foi realizada a partir do acoplamento de um viscosímetro rotativo com um banho termostático. As curvas obtidas mostraram incremento da viscosidade dinâmica com a temperatura para os nanofluidos em relação aos seus fluidos base. Houve também incremento da viscosidade relativa, sobretudo para temperaturas mais elevadas. Os nanofluidos apresentaram comportamento não newtoniano. Para elevadas taxas de cisalhamento, as medições de viscosidade tendem a valores constantes. Correlações entre viscosidade com temperatura e com taxa de cisalhamento foram construídas seguindo funções exponenciais decrescentes e de potência, respectivamente. Os resultados obtidos neste trabalho acrescentam conhecimento à literatura científica sobre a viscosidade e o comportamento reólógico de nanofluidos a baixas temperaturas. / [en] The use of nanofluids in the Thermosciences has been of great interest since it enables a substantial improvement in the heat transfer capacity in thermal machines. This is possible due to the presence particles in suspension, with diameters less than 100 nm, dispersed in conventional fluids. Parameters such as viscosity and thermal conductivity are determining factors in the performance of these materials as thermal fluids in different applications. The objective of the present work was to determine the dynamic viscosity and the shear stress of three distinct nanofluids under controlled temperature conditions (range -10 Celsius degrees to 30 Celsius degrees) at laboratory. In addition, shear rate and rotation rate were also conditioning parameters. The experimental apparatus was assembled coupling a viscometer with a thermal bath. The obtained results showed an increase of the dynamic viscosity with temperature for all nanofluids with respect to their base fluids. An increase of the relative viscosity was also observed especially at higher temperatures. The three nanofluids have shown a non-newtonian behavior. With high shear rates, the measured viscosities tended towards constant values. Curve adjustments were performed between viscosity vs temperature and viscosity vs shear rate using exponential decay function and the Power Law, respectively. The achievements of this research added scientific understanding about the viscosity and rheological behavior of nanofluids at low temperatures.

The objective of this master thesis is to design a robotic work cell for automated insertion of thermostatic heads. The proposed design was based on the comprehensive analysis of the current workplace. By taking the demands of the company and customer into consideration, several possibilities of the robotic work cell design were proposed, from which the most suitable one was chosen and carefully elaborated. During the process of designing, several safety standards had to be taken into consideration in order to mitigate risks. For that purpose, a risk analysis was conducted as well. Using the Siemens Process Simulate software, the proposed robotic work cell concept was verified, including cycle time analysis. The last part of the thesis is an assessment of the initial expenditures of the robotic work cell equipment, as well as the return of the investment calculation. Drawing of the robotic work cell layout is attached to the thesis.

This master‘s thesis deals with the thermal overload trip unit in automatically operated electrical switching devices. The first part of this thesis serves as a basis for a design of thermostatic bimetal element in electrical switching device. The thesis presents important parameters and calculation principles needed for the design of bimetal element. The thesis further describes the operating principle of thermal trip unit and its possible design solutions. The main part is devoted to analytical calculation and measurement of specific thermostatic bimetal type contained in thermal trip unit of molded case circuit breaker. It is measurement of force and deflection, depending on temperature change. In the next part a numerical model of the bimetallic strip was created and its deflection was simulated. The analytical results are compared with the measured and simulated results at the end of the thesis.

The focus of this Master’s thesis is on designing a device for testing the mechanical endurance of thermostatic valves according to the EN215 standard. The endurance tests under the influence of torque and bending moment are the main probléme it deasl with. The thesis contains engineering design of the testing device and it also includes mechanical drawings, design of sensors and measuring algorithm. The design of a water circuit used for water conditioning for the trstiny device is also included.