Modeling and simulation of forced-air cooling of strawberries using variable convective coefficient

In the forced-air cooling process of fruits occurs, besides the convective heat transfer, the mass transfer by evaporation. The energy need in the evaporation is taken from fruit that has its temperature lowered. In this study it has been proposed the use of empirical correlations for calculating the convective heat transfer coefficient as a function of surface temperature of the strawberry during the cooling process. The aim of this variation of the convective coefficient is to compensate the effect of evaporation in the heat transfer process. Linear and exponential correlations are tested, both with two adjustable parameters. The simulations are performed using experimental conditions reported in the literature for the cooling of strawberries. The results confirm the suitability of the proposed methodology.

Low cost driver device for microclimate maintenance in the pre-milking of dairy cattle

Due to the importance of the environment on animal production and thus environmental control, the study aims to build a system for monitoring and control the meteorological variables, temperature and relative humidity, low cost, which can be associated with an evaporative cooling system (ECS). The system development included all the stages of assembly, test and laboratory calibration, and later the validation of the equipment carried in the field. The validation step showed results which allowed concluding that the system can be safely used in the monitoring of these variables. The controller was efficient in management of the microclimate in the waiting corral and allowed the maintenance of the air temperature within the comfort range for dairy cattle in pre-milking with averaged 25.09 ºC during the afternoon. The equipment showed the lower cost (R$ 325.76) when compared to other middle market (R$ 450.00).

The impact of evaporative cooling on the thermoregulation and sensible heat loss of sows during farrowing

Pigs are more sensitive to high environmental temperatures explained by the inability of sweating and panting properly when compared to other species of farmed livestock. The evaporative cooling system might favor the thermal comfort of animals during exposure to extreme environmental heat and reduce the harmful effects of heat stress. The purpose of this study was to assess the sensible heat loss and thermoregulation parameters from lactating sows during summer submitted to two different acclimatization systems: natural and evaporative cooling. The experiment was carried out in a commercial farm with 72 lactating sows. The ambient variables (temperature, relative humidity and air velocity) and sows physiological parameters (rectal temperature, surface temperature and respiratory rate) were monitored and then the sensible heat loss at 21days lactation was calculated. The results of rectal temperature did not differ between treatments. However, the evaporative cooling led to a significant reduction in surface temperature and respiratory rate and a significant increase in the sow's sensible heat loss. It was concluded that the use of evaporative cooling system was essential to increase sensible heat loss; thus, it should reduce the negative effects of heat on the sows' thermoregulation during summer.

Effects of maintenance management procedures in sugarcane mechanic harvesting system equipment

ABSTRACT The aim of this study was to evaluate the effects of modifying the maintenance programming of equipment used in sugarcane mechanical harvesting, by transferring actions that can be planned to periods when machines are inactive due to meal breaks and other working shift transitions stoppages. A simulation model was developed to represent the maintenance procedures of combines, haulouts, and other vehicles used by a harvest team. Scenarios were tested using alternatives for interventions such as refueling, lubrication and harvester blade replacement, enabling strategies to be focused towards better utilization of cutting, loading, and transport (CLT) system equipment. As a result, it was possible to remove one combine and two haulouts, while maintaining current daily production. The maintenance time for harvesters, which refers to corrective maintenance and the transfer of remaining interventions for periods of inactivity, was reduced from 10.0% to 3.5% over the useful period. This study indicates that maintenance management in the sugarcane sector enables the expanded use of equipment, leading to the greater productivity of the CLT system.

Structural and operational optimisation : applications in energy systems

In this work mathematical programming models for structural and operational optimisation of energy systems are developed and applied to a selection of energy technology problems. The studied cases are taken from industrial processes and from large regional energy distribution systems. The models are based on Mixed Integer Linear Programming (MILP), Mixed Integer Non-Linear Programming (MINLP) and on a hybrid approach of a combination of Non-Linear Programming (NLP) and Genetic Algorithms (GA). The optimisation of the structure and operation of energy systems in urban regions is treated in the work. Firstly, distributed energy systems (DES) with different energy conversion units and annual variations of consumer heating and electricity demands are considered. Secondly, district cooling systems (DCS) with cooling demands for a large number of consumers are studied, with respect to a long term planning perspective regarding to given predictions of the consumer cooling demand development in a region. The work comprises also the development of applications for heat recovery systems (HRS), where paper machine dryer section HRS is taken as an illustrative example. The heat sources in these systems are moist air streams. Models are developed for different types of equipment price functions. The approach is based on partitioning of the overall temperature range of the system into a number of temperature intervals in order to take into account the strong nonlinearities due to condensation in the heat recovery exchangers. The influence of parameter variations on the solutions of heat recovery systems is analysed firstly by varying cost factors and secondly by varying process parameters. Point-optimal solutions by a fixed parameter approach are compared to robust solutions with given parameter variation ranges. In the work enhanced utilisation of excess heat in heat recovery systems with impingement drying, electricity generation with low grade excess heat and the use of absorption heat transformers to elevate a stream temperature above the excess heat temperature are also studied.

Locally made equipment

kuv., 22 x 29 cm

Seuraajasuunnitteluprosessi ja sen toimivuus KONE Oyj:n New Equipment Business -liiketoimintayksikössä

Tämä tutkimus käsittelee seuraajasuunnitteluprosessia ja sen toimivuutta. Tutkimus on tapaustutkimus, jossa tutkittava ilmiö eli seuraajasuunnittelu ja kohteena oleva tapaus eli organisaatio KONE Oyj:n yksi liiketoimintayksikkö New Equipment Business, NEB voidaan erottaa toisistaan. Tutkimuksen kohteena on seuraajasuunnitteluprosessin toimivuus tapausorganisaatiossa. Tutkimuksen tarkoituksena on hankkia tietoa ja ymmärtää prosessin toteutumista sekä löytää jo käytössä olevat parhaimmat käytännöt sekä merkittävimmät kehitysalueet. Tutkimuksen lähestymistapa on kvalitatiivinen. Seuraajasuunnitteluprosessin toimivuutta tutkittiin tekemällä teemahaastatteluja tutkimuksen kohteena olevan organisaation eri funktioiden henkilöstöpäälliköiden ja yksiköiden johtajien kanssa. Haastattelujen lisäksi tutkimuksessa käytettiin tausta-aineistona yrityksen sisäisiä arkistointitietoja ja materiaalia. Työn tuloksena saatiin selville, miten seuraajasuunnitteluprosessi toteutuu kohdeorganisaatiossa. Tutkimuksen tulosten perusteella näyttää siltä, että panostamalla talenttien kehitystoimenpiteisiin sekä lisäämällä henkilöiden liikkuvuutta yli organisaatiorajojen voidaan kehittää seuraajasuunnitteluprosessia vastaamaan tulevaisuuden haasteisiin.

Two-dimensional atom localization and Raman cooling of tripod-type atoms

Both atom localization and Raman cooling, considered in the thesis, reflect recent progress in the area of all-optical methods. We focus on twodimensional (2D) case, using a four-level tripod-type atomic scheme for atom localization within the optical half-wavelength as well as for efficient subrecoil Raman cooling. In the first part, we discuss the principles of 1D atom localization, accompanying by an example of the measurement of a spontaneously-emitted photon. Modifying this example, one archives sub-wavelength localization of a three-level -type atom, measuring the population in its upper state. We go further and obtain 2D sub-wavelength localization for a four-level tripod-type atom. The upper-state population is classified according to the spatial distribution, which in turn forms such structures as spikes, craters and waves. The second part of the thesis is devoted to Raman cooling. The cooling process is controlled by a sequence of velocity-selective transfers from one to another ground state. So far, 1D deep subrecoil cooling has been carried out with the sequence of square or Blackman pulses, applied to -type atoms. In turn, we discuss the transfer of atoms by stimulated Raman adiabatic passage (STIRAP), which provides robustness against the pulse duration if the cooling time is not in any critical role. A tripod-type atomic scheme is used for the purpose of 2D Raman cooling, allowing one to increase the efficiency and simplify the realization of the cooling.

Computational studies for the design of process equipment with complex geometries

This study combines several projects related to the flows in vessels with complex shapes representing different chemical apparata. Three major cases were studied. The first one is a two-phase plate reactor with a complex structure of intersecting micro channels engraved on one plate which is covered by another plain plate. The second case is a tubular microreactor, consisting of two subcases. The first subcase is a multi-channel two-component commercial micromixer (slit interdigital) used to mix two liquid reagents before they enter the reactor. The second subcase is a micro-tube, where the distribution of the heat generated by the reaction was studied. The third case is a conventionally packed column. However, flow, reactions or mass transfer were not modeled. Instead, the research focused on how to describe mathematically the realistic geometry of the column packing, which is rather random and can not be created using conventional computeraided design or engineering (CAD/CAE) methods. Several modeling approaches were used to describe the performance of the processes in the considered vessels. Computational fluid dynamics (CFD) was used to describe the details of the flow in the plate microreactor and micromixer. A space-averaged mass transfer model based on Fick’s law was used to describe the exchange of the species through the gas-liquid interface in the microreactor. This model utilized data, namely the values of the interfacial area, obtained by the corresponding CFD model. A common heat transfer model was used to find the heat distribution in the micro-tube. To generate the column packing, an additional multibody dynamic model was implemented. Auxiliary simulation was carried out to determine the position and orientation of every packing element in the column. This data was then exported into a CAD system to generate desirable geometry, which could further be used for CFD simulations. The results demonstrated that the CFD model of the microreactor could predict the flow pattern well enough and agreed with experiments. The mass transfer model allowed to estimate the mass transfer coefficient. Modeling for the second case showed that the flow in the micromixer and the heat transfer in the tube could be excluded from the larger model which describes the chemical kinetics in the reactor. Results of the third case demonstrated that the auxiliary simulation could successfully generate complex random packing not only for the column but also for other similar cases.

Reflectance indices as a diagnostic tool for weed control performed by multipurpose equipment in precision agriculture

Several tools of precision agriculture have been developed for specific uses. However, this specificity may hinder the implementation of precision agriculture due to an increasing in costs and operational complexity. The use of vegetation index sensors which are traditionally developed for crop fertilization, for site-specific weed management can provide multiple utilizations of these sensors and result in the optimization of precision agriculture. The aim of this study was to evaluate the relationship between reflectance indices of weeds obtained by the GreenSeekerTM sensor and conventional parameters used for weed interference quantification. Two experiments were conducted with soybean and corn by establishing a gradient of weed interference through the use of pre- and post-emergence herbicides. The weed quantification was evaluated by the normalized difference vegetation index (NDVI) and the ratio of red to near infrared (Red/NIR) obtained using the GreenSeekerTM sensor, the visual weed control, the weed dry matter, and digital photographs, which supplied information about the leaf area coverage proportions of weed and straw. The weed leaf coverage obtained using digital photography was highly associated with the NDVI (r = 0.78) and the Red/NIR (r = -0.74). The weed dry matter also positively correlated with the NDVI obtained in 1 m linear (r = 0.66). The results indicated that the GreenSeekerTM sensor originally used for crop fertilization could also be used to obtain reflectance indices in the area between rows of crops to support decision-making programs for weed control.

Lujien painelaiteterästen hitsaus

Työn tavoitteena oli tutkia lujan nuorrutetun painelaiteteräksen P500QL2 hitsattavuutta ja koehitsausten avulla löytää optimaaliset hitsausparametrit ja lämmöntuonti teräksen hitsaukseen. Työn tavoitteena oli myös selvittää ja käsitellä kaikkien painelaiteterässtandardissa esitettyjen lujien painelaiteterästen hitsauksessa huomioon otettavia asioita. Työn teoriaosuudessa käsitellään lujien painelaiteterästen hitsauksessa huomioitavia erityispiirteitä, kuten lämmöntuontia, jäähtymisaikaa, esilämmitystä sekä hitsausaineiden valintaa. Lisäksi teoriaosuudessa käsitellään painelaitteiden valmistusta, painelaiteterässtandardiin kuuluvia lujia painelaiteteräksiä sekä keinoja lujien terästen hitsattavuuden arviointiin. Työn kokeellisessa osassa tutkittiin aineenvahvuudeltaan 50 mm paksun P500QL2-teräksen päittäisliitoksen mekaanisia ominaisuuksia eri lämmöntuonneilla hitsattuna. Kokeellisessa osassa tutkittiin myös myöstön poisjättämisen vaikutuksia liitoksen mekaanisiin ominaisuuksiin. Mekaanisia ominaisuuksia tutkittiin toteuttamalla koekappaleiden aineenkoetus menetelmäkoestandardin vaatimuksia soveltaen. Tutkimuksessa käytettyjä testausmenetelmiä olivat silmämääräinen tarkastus, magneettijauhetarkastus, ultraäänitarkastus, mikro- ja makrorakennetarkastelu, kovuuskokeet, vetokokeeet ja iskukokeet. Testauksessa saatujen tulosten avulla lujan painelaiteteräksen P500QL2 hitsaukseen laadittiin alustava hitsausohje. Hitsausliitosten testauksessa saatujen tulosten perusteella havaittiin hitsien lujuuden ja kovuuden laskevan lämmöntuonnin kasvaessa. Hitsausliitosten iskusitkeysominaisuudet olivat erinomaiset vielä suurellakin lämmöntuonnilla, mutta liitosten murtovenymäarvot laskivat lämmöntuonnin kasvaessa. Myöstön havaittiin parantavan hitsin mekaanisia ominaisuuksia huomattavasti. Tutkimuksen tulosten perusteella painelaiteteräs P500QL2 on hitsattavissa suurella lämmöntuonnilla ja suurella tuottavuudella liitoksen täyttäessä painelaitevalmistuksen edellyttämät vaatimukset.

Wind Turbine Direct-Drive Permanent-Magnet Generator with Direct Liquid Cooling for Mass Reduction

Today’s electrical machine technology allows increasing the wind turbine output power by an order of magnitude from the technology that existed only ten years ago. However, it is sometimes argued that high-power direct-drive wind turbine generators will prove to be of limited practical importance because of their relatively large size and weight. The limited space for the generator in a wind turbine application together with the growing use of wind energy pose a challenge for the design engineers who are trying to increase torque without making the generator larger. When it comes to high torque density, the limiting factor in every electrical machine is heat, and if the electrical machine parts exceed their maximum allowable continuous operating temperature, even for a short time, they can suffer permanent damage. Therefore, highly efficient thermal design or cooling methods is needed. One of the promising solutions to enhance heat transfer performances of high-power, low-speed electrical machines is the direct cooling of the windings. This doctoral dissertation proposes a rotor-surface-magnet synchronous generator with a fractional slot nonoverlapping stator winding made of hollow conductors, through which liquid coolant can be passed directly during the application of current in order to increase the convective heat transfer capabilities and reduce the generator mass. This doctoral dissertation focuses on the electromagnetic design of a liquid-cooled direct-drive permanent-magnet synchronous generator (LC DD-PMSG) for a directdrive wind turbine application. The analytical calculation of the magnetic field distribution is carried out with the ambition of fast and accurate predicting of the main dimensions of the machine and especially the thickness of the permanent magnets; the generator electromagnetic parameters as well as the design optimization. The focus is on the generator design with a fractional slot non-overlapping winding placed into open stator slots. This is an a priori selection to guarantee easy manufacturing of the LC winding. A thermal analysis of the LC DD-PMSG based on a lumped parameter thermal model takes place with the ambition of evaluating the generator thermal performance. The thermal model was adapted to take into account the uneven copper loss distribution resulting from the skin effect as well as the effect of temperature on the copper winding resistance and the thermophysical properties of the coolant. The developed lumpedparameter thermal model and the analytical calculation of the magnetic field distribution can both be integrated with the presented algorithm to optimize an LC DD-PMSG design. Based on an instrumented small prototype with liquid-cooled tooth-coils, the following targets have been achieved: experimental determination of the performance of the direct liquid cooling of the stator winding and validating the temperatures predicted by an analytical thermal model; proving the feasibility of manufacturing the liquid-cooled tooth-coil winding; moreover, demonstration of the objectives of the project to potential customers.

Promoting Cleantech in Emerging Markets: Business Model for Waste Pre-treatment Equipment in China

Waste incineration is becoming increasingly widespread method of waste disposal in China. Incineration plants mostly use grate and circular fluidized bed (CFB) technology. Waste combustion in cement production is also beginning to gradually increase. However, Chinese waste composition is causing problems for the energy utilization. Mechanical waste pre-treatment optimizes the combustion process and facilitates the energy recovery. The objective of this study is to identify how Western waste pre-treatment manufacturer could operate in Chinese markets. Chinese waste management industry is reviewed via PESTEL analysis. The current state and future predictions of grate and CFB incineration as well as cement manufacturing are monitored. Grate combustion, which requires lesser waste pre-treatment, is becoming more common at the expense of CFB incineration in China. The most promising future for waste treatment is in cement production industry. Waste treatment equipment manufacturer should try to create pilot projects with biggest cement producers with a view of growing co-operation in the future.

The demand-supply balancing process in supply chain management - case mining & metals industry equipment

The aim of this thesis is to search how to match the demand and supply effectively in industrial and project-oriented business environment. The demand-supply balancing process is searched through three different phases: the demand planning and forecasting, synchronization of demand and supply and measurement of the results. The thesis contains a single case study that has been implemented in a company called Outotec. In the case study the demand is planned and forecasted with qualitative (judgmental) forecasting method. The quantitative forecasting methods are searched further to support the demand forecast and long term planning. The sales and operations planning process is used in the synchronization of the demand and supply. The demand forecast is applied in the management of a supply chain of critical unit of elemental analyzer. Different meters on operational and strategic level are proposed for the measurement of performance.