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Working fluids for thermal heat pump cycles have been studied. Methanol in conjunction with a mixture of inorganic bromides has been identified as being suitable for transforming heat from temperatures below zero centigrade. A computer programme was written in order to calculate the performance of such a combination, and its accuracy was verified by comparing its predictions with the actual performance of existing (commercial) heat pumps and chillers using combinations other than the above. Transport and other properties of the mixture have been measured, including vapour pressure, specific heat, viscosity, relative density, solubility, thermal conductivity, surface tension, heat of absorption, absorption coefficient, and hence mass diffusivity. An intermittent absorption heat pump was constructed and its performance measured. The tests demonstrated that it was capable of pumping heat from -10 °C up to 74 °C.

Twin-screw multiphase pumps experience a severe decrease in efficiency, even the breakdown of pumping function, when operating under wet gas conditions. Additionally, field operations have revealed significant vibration and thermal issues which can lead to damage of the pump internals and expensive repairs and maintenance. There are limited models simulating the performance of twin-screw pump under these conditions. This project develops a pump-user oriented simulator to model the performance of twin-screw pumps under wet gas conditions. Experimental testing is conducted to verify the simulation results. Based on the simulations, an innovative solution is presented to improve the efficiency and prevent the breakdown of pumping function. A new model is developed based upon a previous Texas A&M twin-screw pump model. In this model, both the gas slip and liquid slip in the pump clearances are simulated. The mechanical model is coupled with a thermodynamic model to predict the pressure and temperature distribution along the screws. The comparison of experimental data and the predictions of both isothermal and non-isothermal models show a better match than previous models with Gas Volume Fraction (GVF) 95% and 98%. Compatible with the previous Texas A&M twin-screw pump model, this model can be used to simulate the twin-screw pump performance with GVF from 0% to 99%. Based on the effect of liquid viscosity, a novel solution is investigated with the newly developed model to improve the efficiency and reliability of twin-screw pump performance with GVF higher than 94%. The solution is to inject high viscosity liquid directly into the twin-screw pump. After the simulations of several different scenarios with various liquid injection rates and injection positions, we conclude that the volumetric efficiency increases with increasing liquid viscosity and injecting liquid in the suction is suggested.

Sweden’s energy consumption is divided into three major sectors. One of them is the industry sector. One third of Sweden’s energy consumption is converted in the industries. The chemical industry is one of those industries with great energy needs. This thesis looks into energy efficiency in industry, in particular the plastics manufacturing industry. Efficiency concerning heat exchangers, their fouling resistance and also pumps. This thesis also relates to the industry in the big picture as heat exchangers and pumps are widely used and these has a great energy and environmental efficiency. This thesis presents an algorithm especially developed for this issue. The thesis has been written by dividing the work into measurements and data, implementation and analysis. The result of this thesis is an Excel-sheet that may be used to calculate the fouling resistance in a plate heat exchanger. / Sveriges energianvändning är uppdelad i tre stora sektorer. Ett av dem är industrin. En tredjedel av Sveriges energiförbrukning omvandlas inom industrierna. Kemiindustrin är av dem industrier som har stort energibehov. Detta examensarbete tar upp effektivisering inom industrin, närmre sett plasttillverkningsindustrin. Effektiviseringen berör värmeväxlare och dess foulingresistans och även pumpar. Examensarbetet kan spegla industrin i den stora bilden då värmeväxlare och pumpar finns väldigt utspritt och effektiviseras dessa har en stor energi och miljöeffektivisering gjorts. För att energieffektivisera inom detta examensarbete har en beräkningsalgoritm tagits fram. Arbetet har delats upp i mätvärden, beräkningar genomförande och analys. Resultatet blev en Excel-ark som kan användas för att beräkna foulingresistansen i en plattvärmeväxlare.

Thesis (Ph.D.)--University of Wyoming, 2007. / Title from PDF title page (viewed on June 17, 2009). Includes bibliographical references (p. 167-178).

This diploma thesis deals with centrifugal pump running as a turbine. Basic working principles of a pump are included, both in pump and turbine regime. Experimental data obtained from laboratory test bed are compared with CFD simulation on slightly simplified geometry. Obtained results are then processed using spectrogram. Influence of time step and mesh size on results is also researched.

The engine cooling system is an important part of the engine’s performance to achieve optimum temperatures in cylinders and provide cooling to subsystems. With increasing emission demands from legislation, further development of the cooling system is necessary. An important component in the engine cooling system is the pump that produces the necessary flow rate to cool down the components. The pump is connected to the drive shaft with a pulley so improvements in the pumps efficiency will directly affect the fuel efficiency of the vehicle. With more variations and increasingly complex system design different performance stages of the pump are necessary to provide desired flow rates depending on system design. To enable a rapid design of performance stages of pumps, a calculation model is constructed to predict the performance of an engine cooling pump based on the geometry of the impeller and pump casing. The model includes the main head losses that occur within a centrifugal pump both in the impeller and pump casing. The model is based on quasi one-dimensional calculations of velocity triangles in impeller and pump casing. The head losses are modelled with correlations from literature that are compared to test data from reference pumps. The developed model provides a pump - , hydraulic efficiency – and power curve based on main geometrical parameters. A design tool and procedure is constructed to suggest main geometry parameters for the impeller based on a desired operational point. The design tool is constructed on design coefficients based on reference pumps test data and correlations from literature. Together with the calculation model an impeller flow channel can be designed to achieve the desired operational point. Two impellers are designed and manufactured by rapid prototyping that are tested by an experimental test to verify the model and design tool. The result show that the calculation model captures the general behaviour of the pump curve and is within 1-10% accuracy. The calculation model and the design tool are designed to assess the performance of the main geometry parameters in the impeller and pump casing. Further optimization and studies of the complete flow field to assess secondary flows and cavitation behaviour can be done by numerical methods. The calculation model and design tool constructed provides a rapid way of designing new impellers and an easy method to perform parameter studies on changes in impeller geometry. / Motorns kylsystem är en viktig del av motorns prestanda för att uppnå optimal temperatur i cylindrarna och för att tillhandahålla kylning till de olika delsystem. Med ökade utsläppskrav från lagstiftning har kylsystemet och dess fortsatta utveckling en viktig roll för att möta dessa. En viktig komponent i kylsystemet är pumpen som tillhandahåller den nödvändiga flödeshastigheten för att kyla ner de ingående komponenterna.  Pumpen drivs av drivaxeln med remdrift vilket medför att verkningsgraden på pumpen direkt påverkar bränsleförbrukningen. Utvecklingen går mot att kylsystemet blir mer varierat och snabbt ska kunna anpassa sig till nya kylbehov vilket medför att olika prestandasteg på pumpen är nödvändiga för att kunna garantera tillräcklig flödeshastighet. För att förkorta ledtiderna i processen av att designa olika prestandasteg av en kylvätskepump har en beräkningsmodell utvecklats som kan förutsäga pumpens prestanda baserat på impellerns och pumphusets geometri. I modellen ingår de största strömningsförlusterna som uppstår i en centrifugalpump både i impellern och i pumphuset. För att modellera förlusterna som uppstår används korrelationer som är anpassade och korrelerade mot test data från referenspumpar. Modellen beräknar en pumpkurva, hydraulisk verkningsgradskurva och en effektkurva baserat på pumpens geometri. Ett designverktyg och ett tillvägagångssätt för att designa impellrar är också framtaget som är baserat på beräkningsmodellen samt en given designpunkt. Designverktyget använder olika designkoefficienter som är baserade på tidigare test data samt etablerade korrelationer. Tillsammans med beräkningsmodellen kan flödeskanalen designas baserat på en given designpunkt av flöde, tryckhöjd och rotationshastighet. Med hjälp av designverktyget är två impellrar designade och tillverkade genom friformsframställning vilka provas för att verifiera modellen och designverktyget. Resultatet visar att beräkningsmodellen kan prediktera pumpkurvans beteende med en noggrannhet på 1-10%. Beräkningsmodellen samt designverktyget är baserat på de huvudsakliga geometriparametrarna i impellern och pumphuset. För att fullständigt analysera flödesfältet i pumpen samt optimera designen och bedöma kavitationsrisken krävs en numerisk analys.  Beräkningsmodellen och designverktyget ger ett snabbt tillvägagångssätt för att designa och utvärdera prestandan i en pump samt göra enkla parameterstudier av designparameterar i pumpen.

Mosquitoes drink using a pair of in-line muscular pumps in the head that draw liquid food through a long drinking channel termed as proboscis. Experimental investigations of mosquito drinking using synchrotron x-ray indicate two modes of drinking, a predominantly occurring continuous mode in which the anterior cibarial and posterior pharyngeal pumps expand cyclically at a constant phase difference and an isolated burst mode in which the pharyngeal pump expansion is several orders of magnitude larger than in the continuous mode. The objective of this thesis is to explain the mechanics and functional implication of this two-pump dual mode drinking of a mosquito. A reduced order mathematical model suggests that the primary role of the pharyngeal pump is in the burst mode. Since the precise geometry of the pump during drinking is yet not known, the drinking mechanism is modeled using different pump geometries based on morphological constraints in the animal. The model shows the continuous mode as being more effective in terms of energy expenditure, while the burst mode creates a large pressure difference across the proboscis which might be used to clear an obstruction in the channel or prime the channel. The hypothesis regarding the ability of a mosquito to self-clear an obstruction is analyzed by modeling the presence of an air bubble inside the system. The model indicates that air bubbles maybe able to stop flow during continuous mode drinking, and these same bubbles can be cleared by switching temporarily to burst mode drinking. / Master of Science

This thesis presents a novel, low cost, high precision , and efficient design for an electro-hydrostatic circuit for single rod hydraulic cylinders. The design is the main contribution of candidate to fulfill the regiments of PhD degree. The challenge of existing deigns of electro-hydrostatic circuits for single-rod cylinders is using one pump to control the cylinder under switching (resistive-assistive) loads. The proposed circuit utilizes off-the-shelf industrial elements. It uses two counterbalance valves to manage switching loads and one on/off solenoid valve to redirect the differential flow of the single rod cylinder to tank. A set of simulation studies is conducted using Simhydraulic tools of Matlab in order to study performances of the proposed circuit and compare it with existing designs. Pump-controlled hydraulic circuit for double rod cylinders was developed and is widely used by industry. It is used as the benchmark for simulation studies. As well, the proposed circuit and two major existing pump-controlled circuits for single rod cylinders are compared to the benchmark circuit. Evaluations are conducted by comparing chamber pressure responses as well as pressure vs position of the cylinder end-effector for each individual circuit. Results indicate that the proposed circuit performed as well as the benchmark circuit by controlling pressures to both sides of the cylinder at the same time. Moreover, the load in the proposed circuit is more controllable compared to the benchmark circuit. Experimental results, obtained from the developed test rig, validate accuracy of the simulation model. Maximum steady state position error of 0.06 mm applications is experimentally observed when the test rig is tested under different loading conditions with various amplitudes and frequencies. The circuit consumes up to 20% of the energy that is required by a valve controlled circuit given the same sinusoidal tracking signal. The relative efficiency of the proposed circuit over a valve xii controlled circuit depends on the pattern and frequency of the tracking signal. In all the experiments, a simple proportional controller, which uses readings of a linear position transducer, is employed. The use of the proportional controller makes the proposed circuit easy to implement and shows it is good candidate for industrial applications. The accuracy of the position response of the proposed circuit indicates, it is a good candidate for robotic applications too. / May 2016

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