Chilled water systems constitute a major portion of energy consumption in air conditioning systems of commercial buildings and process cooling of manufacturing plants. These systems do not operate optimally in most of the cases because of the operating parameters set and/or the components used. A Chilled water system analysis tool software (CWSAT) is developed as a primary screening tool for energy evaluation. This tool quantifies the energy usage of the various chilled water systems and typical measures that can be applied to these systems to conserve energy. The tool requires minimum number of inputs to analyze the component-wise energy consumption and incurred overall cost. This thesis also examines various energy conservation measures that are available for chilled water systems. The components, arrangements, and the common energy conservation opportunities for chilled water systems are presented. The new version of the tool is developed in Object Oriented Programming Language Microsoft Visual Basic.Net© to maintain the tool latest with current technology, add and expand capabilities and avoid obsolescence. Many Improvements to the previous tool are made to improve quality and the types of the systems the tool can handle. The development of the new routines and interfaces is also accommodated in the new version to make the tool universal. In order to determine the accuracy of the new version of the tool, a comparison is made between the results from the previous and new version of the tool. The results of the comparisons are presented.

Permanent magnet brushless dc (PMBDC) and synchronous machines (PMSM) drives are favored in variable speed applications for their high efficiency operation. Energy efficiency improvement in such motor drives is of interest in recent times because of rising cost of energy. Accordingly, two current control options for improving efficiency of these drives are taken for study and they are; (i) injecting sinusoidal and non-sinusoidal currents in PMBDC machines and (ii) lowering switching frequency of inverter driving the PMSM but without having significant low ordered sidebands of currents. Both these methods are applicable to existing types of permanent magnet motors and hence do not upset their existing optimized designs. / Ph. D.

This thesis analyses long term and short term environmental effects on geothermal power plant performance and discusses adaptive ways to improve performance. Mokai 1 geothermal power plant has been used as a case study for this investigation. Mokai 1 is a combined cycle plant where the binary cycles are air-cooled. The plant performance of an air-cooled binary cycle geothermal power plant is dependent on the environment (resource characteristics as well as weather conditions). For modelling such a power plant, two time scales are of interest: the yearly basis for aggregate plant performance for design and operations; and the daily basis for hourly plant performances for an accurate dispatch prediction. Adaptive methodology for long term performance improvement has been introduced in this work which would save money and effort in the future by keeping the provisions to adapt to changes in resource characteristics based on geothermal reservoir modelling. The investigation was carried out using a steady state computer simulator of Mokai 1 geothermal power plant. The steady sate simulator was built specifically for this work. The deviation in performance of various components is less than 5% compared to the original plant design. The model is very generic and it can be used for other plants with simple adaptation or can be used for future plant design. One of the main contributions of this work is an iterative method for modelling the environmental effect on short term performance on the air-cooled organic Rankine cycle. The ambient temperature is identified as the most influencing parameter on short term performance which influences the performance of the whole cycle in two ways. Firstly, by changing the equilibrium pressure inside the condenser, the turbine outlet pressure changes and hence, the turbine pressure ratio also changes. The turbine pressure ratio is a major parameter determining power generated by a turbine; therefore, the plant output is affected. Secondly, by changing the condenser outlet temperature with the ambient temperature, the pump inlet and outlet condition and consequently vaporizer equilibrium temperature and pressure are influenced. The developed method sought the equilibrium conditions of both condenser and vaporizer iteratively. In short, ORC cycle shifts on the T-s plane depending on the ambient temperature. This method iteratively seeks the shifted ORC on the T,s plane. Two case studies have been carried out to demonstrate the method. The developed method shows robustness and converges exponentially. The model is effective for cycles that use saturated vapour as well as superheated vapour. The model essentially assumes steady state operation of the power cycle. The possible unit time where this model can be applied is bounded by the time required by a system to come into steady state. The saturated vapour cycle yielded average error 4.20% with maximum error 9.25% and the superheated vapour cycle yielded average error 2.12% with maximum error 5.60%. The main advantage of the developed method is that it requires a minimum number of inputs: condenser (p,T), vaporizer (p,T), condenser heat load, turbine efficiency (overall), pump work and the extremum conditions of all the components. These inputs should represent typical operating conditions of a plant. The model can predict the appropriate plant performance depending on the system heat input (geothermal fluid flow in this case) and the heat sink temperature. As the method is based on basic thermodynamics rather than empirical or semi-empirical approaches, this method is widely applicable. The main focus of this work is on the ORC but the developed method is applicable to any closed Rankine cycle. In addition, application of the developed iterative method to predict plant performance based on mean yearly weather data is also discussed in the thesis. Water-augmented cooling system and optimization of plant operating point parameters have been proposed as adaptive measures to improve short term performance. Developed iterative method has been used for the short term performance analysis. The water-augmented cooling system is specifically suitable to mitigate the reduced power output during the summer. The simulated average gain in power during the summer (Jan, Feb, Nov and Dec) of an ORC of Mokai 1 geothermal power plant by incorporating a water-augmented cooling system was 2.3% and the average gain for the whole year was 1.6% based on the weather data of Taupo for the year 2005. A cost benefit analysis showed that water-augmented cooling system is more economical compared to other alternative renewable energies considered to meet summer peak demand. From the green house gas emissions perspective, water-augmented cooling is a better option than the gas fired peaking plants. Adaptive approach for short term performance improvement by optimizing operating point parameters of an air-cooled binary cycle has huge potential with possible maximum improvement in power output by about 50%. The optimization takes in to account the effects of the geothermal resource characteristics and the weather conditions. The optimization is achieved by manipulating cycle mass flow rate and vaporizer equilibrium condition. Further study on the optimizing operating points to achieve improved short term performance has been recommended for future work.

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År 2002 kom EU-direktivet om byggnaders energiprestanda vilket senare ledde till lagen om energideklarationer som hade som syfte att skapa ett effektivt styrmedel för energianvändning i Sverige. Brister med systemet som ett effektivt styrmedel har sedan införandet av lagen uppdagats. Syftet med arbetet är att ta fram vilka metoder som energiexperterna använder sig av vid framtagning av förslag till energieffektivisering och se om metodvalet har någon påverkan på kvalitén av förslaget. Följande frågeställningar har hanterats: Vilka metoder används vid framtagning av förslag till energieffektivisering? Hur påverkar metoderna kvalitén på energiexperternas förslag till energieffektivisering? Vad är energiexperternas syn på arbetet med att ta fram förslag till energieffektivisering? Målet med studien är att öka kvalitén på åtgärdsförslagen i energideklarationer. För kunna genomföra granskningen har en enkätundersökning och sju intervjuer genomförts med energiexperter registrerade i Skåne. Resultatet av enkätundersökningen visar energiexperternas metodval i form av användande av beräkningsprogram, handberäkning, erfarenhetsmässiga antaganden och besiktning av byggnaden samt energiexpertens syn på arbetet med att ta fram förslag till energieffektivisering. Resultatet av intervjuerna visar energiexperternas tillvägagångssätt, syn på kvalitet i åtgärdsförslag samt syn på arbetet med energideklarationer. Energiexperternas arbete med att ta fram energieffektiviserande åtgärder grundas till stor del på besiktningen av byggnaden de ska energideklarera tillsammans med de underlag energiexperten får av fastighetsägaren. Jämförelsen av energiexperternas metoder visade att kvalitén i åtgärdsförslag inte avgörs av vilken beräkningsmetod som används utan snarare av energiexpertens erfarenhet och förmåga att identifiera kostnadseffektiva åtgärdsförslag under besiktning och vid granskning av underlag. Energiexperternas syn på arbetet med att ta fram åtgärdsförslag till energieffektivisering är varierade. Flera anser att arbetet med att ta fram kostnadseffektiva åtgärdsförslag är enkelt och systemet med energideklarationer fungerar som det ska medans andra anser att det finns brister i systemet och att arbetet med att ta fram åtgärdsförslag skulle kunna förbättras. / Since the EU-directive about energy performance of buildings in 2002, the Swedish government passed a law about energy declaration of buildings that came into effect in 2009. From that point forwards buildings have been required to have an energy declaration stating the buildings energy performance and also including suggestions of energy efficiency improvements that can be made for the building. Responsible for producing energy declarations are energy experts whom have been evaluated by certificate authority to be fit for doing energy declarations. The purpose of this study has been to find out which methods the energy experts use when developing proposals for energy efficiency improvments and to see if the choice of method has any impact on the quality of proposed improvements. Questions that have been addressed are: What methods are used when making proposals for energy efficiency improvements? How do the methods affect the quality of proposed energy efficiency improvements? What are the energy experts' view on their work of producing proposals for energy efficiency? The study was carried out by doing a survey and several interviews with energy experts. The results show that the energy experts' work to propose energy efficiency improvements is largely based on the inspection of the building together with the building data that the energy expert gets access to. Comparison of the energy experts' methods showed that the quality of proposed energy efficiency improvements is not determined by the calculation method used but rather by the energy expert's experience and ability to identify cost-effective energy efficiency improvements. The energy experts' views on the work of developing proposed energy efficiency improvements are mixed.