Energy efficient and economic renovation of residential buildings with low-temperature heating and air heat recovery

With the building sector accounting for around 40% of the total energy consumption in the EU, energy efficiency in buildings is and continues to be an important issue. Great progress has been made in reducing the energy consumption in new buildings, but the large stock of existing buildings with poor energy performance is probably an even more crucial area of focus. This thesis deals with energy efficiency measures that can be suitable for renovation of existing houses, particularly low-temperature heating systems and ventilation systems with heat recovery. The energy performance, environmental impact and costs are evaluated for a range of system combinations, for small and large houses with various heating demands and for different climates in Europe. The results were derived through simulation with energy calculation tools. Low-temperature heating and air heat recovery were both found to be promising with regard to increasing energy efficiency in European houses. These solutions proved particularly effective in Northern Europe as low-temperature heating and air heat recovery have a greater impact in cold climates and on houses with high heating demands. The performance of heat pumps, both with outdoor air and exhaust air, was seen to improve with low-temperature heating. The choice between an exhaust air heat pump and a ventilation system with heat recovery is likely to depend on case specific conditions, but both choices are more cost-effective and have a lower environmental impact than systems without heat recovery. The advantage of the heat pump is that it can be used all year round, given that it produces DHW. Economic and environmental aspects of energy efficiency measures do not always harmonize. On the one hand, lower costs can sometimes mean larger environmental impact; on the other hand there can be divergence between different environmental aspects. This makes it difficult to define financial subsidies to promote energy efficiency measures.

Evaluation of a thermally driven heat pump for solar heating and cooling applications

Exploiting solar energy technology for both heating and cooling purposes has the potential of meeting an appreciable portion of the energy demand in buildings throughout the year. By developing an integrated, multi-purpose solar energy system, that can operate all twelve months of the year, a high utilisation factor can be achieved which translates to more economical systems. However, there are still some techno-economic barriers to the general commercialisation and market penetration of such technologies. These are associated with high system and installation costs, significant system complexity, and lack of knowledge of system implementation and expected performance. A sorption heat pump module that can be integrated directly into a solar thermal collector has thus been developed in order to tackle the aforementioned market barriers. This has been designed for the development of cost-effective pre-engineered solar energy system kits that can provide both heating and cooling. This thesis summarises the characterisation studies of the operation of individual sorption modules, sorption module integrated solar collectors and a full solar heating and cooling system employing sorption module integrated collectors. Key performance indicators for the individual sorption modules showed cooling delivery for 6 hours at an average power of 40 W and a temperature lift of 21°C. Upon integration of the sorption modules into a solar collector, measured solar radiation energy to cooling energy conversion efficiencies (solar cooling COP) were between 0.10 and 0.25 with average cooling powers between 90 and 200 W/m2 collector aperture area. Further investigations of the sorption module integrated collectors implementation in a full solar heating and cooling system yielded electrical cooling COP ranging from 1.7 to 12.6 with an average of 10.6 for the test period. Additionally, simulations were performed to determine system energy and cost saving potential for various system sizes over a full year of operation for a 140 m2 single-family dwelling located in Madrid, Spain. Simulations yielded an annual solar fraction of 42% and potential cost savings of €386 per annum for a solar heating and cooling installation employing 20m2 of sorption integrated collectors.

Emissions from realistic operation of residential wood pellets heating systems

Emissions from residential combustion appliances vary significantly depending on the firing behaviours and combustion conditions, in addition to combustion technologies and fuel quality. Although wood pellet combustion in residential heating boilers is efficient, the combustion conditions during start-up and stop phases are not optimal and produce significantly high emissions such as carbon monoxide and hydrocarbon from incomplete combustion. The emissions from the start-up and stop phases of the pellet boilers are not fully taken into account in test methods for ecolabels which primarily focus on emissions during operation on full load and part load. The objective of the thesis is to investigate the emission characteristics during realistic operation of residential wood pellet boilers in order to identify when the major part of the annual emissions occur. Emissions from four residential wood pellet boilers were measured and characterized for three operating phases (start-up, steady and stop). Emissions from realistic operation of combined solar and wood pellet heating systems was continuously measured to investigate the influence of start-up and stop phases on total annual emissions. Measured emission data from the pellet devices were used to build an emission model to predict the annual emission factors from the dynamic operation of the heating system using the simulation software TRNSYS. Start-up emissions are found to vary with ignition type, supply of air and fuel, and time to complete the phase. Stop emissions are influenced by fan operation characteristics and the cleaning routine. Start-up and stop phases under realistic operation conditions contribute 80 – 95% of annual carbon monoxide (CO) emission, 60 – 90% total hydrocarbon (TOC), 10 – 20% of nitrogen oxides (NO), and 30 – 40% particles emissions. Annual emission factors from realistic operation of tested residential heating system with a top fed wood pelt boiler can be between 190 and 400 mg/MJ for the CO emissions, between 60 and 95 mg/MJ for the NO, between 6 and 25 mg/MJ for the TOC, between 30 and 116 mg/MJ for the particulate matter and between 2x10-13 /MJ and 4x10-13 /MJ for the number of particles. If the boiler has the cleaning sequence with compressed air such as in boiler B2, annual CO emission factor can be up to 550 mg/MJ. Average CO, TOC and particles emissions under realistic annual condition were greater than the limits values of two eco labels. These results highlight the importance of start-up and stop phases in annual emission factors (especially CO and TOC). Since a large or dominating part of the annual emissions in real operation arise from the start-up and stop sequences, test methods required by the ecolabels should take these emissions into account. In this way it will encourage the boiler manufacturers to minimize annual emissions. The annual emissions of residential pellet heating system can be reduced by optimizing the number of start-ups of the pellet boiler. It is possible to reduce up to 85% of the number of start-ups by optimizing the system design and its controller such as switching of the boiler pump after it stops, using two temperature sensors for boiler ON/OFF control, optimizing of the positions of the connections to the storage tank, increasing the mixing valve temperature in the boiler circuit and decreasing the pump flow rate. For 85 % reduction of start-ups, 75 % of CO and TOC emission factors were reduced while 13% increase in NO and 15 % increase in particle emissions was observed.

Influence of egg pre-storage heating period and storage length on incubation results

This experiment aimed at evaluating the influence of different heating times of settable eggs of Cobb 500® broiler breeders before submitting them to different storage periods on egg weight loss, embryo mortality, and hatchability. A total number of 1,980 eggs were distributed in a completely randomized experimental design with a 3 x 3 factorial arrangement, comprising nine treatments with 22 replicates of 10 eggs each. The following factors were analyzed: pre-storage heating periods (0, 6, 12 hours at 36.92°C) and storage periods (4, 9, 14 days at 12.06°C). After storage, eggs were incubated under usual conditions, and were transferred to the hatcher at 442 hours of incubation. Eggs were weighed before heating, incubation, and transference to determine weight loss. Partial hatchability was determined at 480 hours, and total hatchability at 498 hours of incubation. Embryo mortality was determined in non-hatched eggs. It was concluded that heating eggs for six hour before storage improves incubation results as it decreases incubation length and late embryo mortality, therefore its use can be indicated in commercial operations. Storing eggs for 14 days and pre-heating for 14 days and pre-heating for 12 hours severely impair incubation results, and therefore are not recommended.

Influence of egg pre-storage heating period and storage length on the digestive tract of newly-hatched broiler chicks

An experiment was carried out to evaluate the effect of different heating times of settable eggs of Cobb 500® broiler breeders before submitting them to different storage periods on body weight, digestive tract organ weights, and intestinal mucosa morphology of newly-hatched chicks. Settable eggs were distributed in a completely randomized experimental design with a 3 x 3 factorial arrangement: pre-storage heating periods (0, 6, 12 hours at 36.92°C) and storage periods (4, 9, 14 days at 12.06°C). Body weight and relative weights of the yolk sac, heart, liver, proventriculus+gizzard, and intestinal segments were measured in chicks hatching at 480 and 498 hours of incubation. Villi height, width and perimeter, and crypt depth (ìm) were measured in duodenal histological sections. It was concluded that pre-storage heating for six hours of eggs stored for four or nine days increases small intestine weight of newly-hatched chicks, but does not influence the morphology of the duodenal mucosa. Pre-storage heating for 12 hours negatively influences body weight and duodenal mucosa development, and therefore this practice is not recommended. Storage length does not have consistent effect on body weight and development of the gastrointestinal tract.

Equilíbrio líquido-líquido de sistemas aquosos com tensoativos polietoxilados: dados experimentais e modelagem

The nonionic surfactants when in aqueous solution, have the property of separating into two phases, one called diluted phase, with low concentration of surfactant, and the other one rich in surfactants called coacervate. The application of this kind of surfactant in extraction processes from aqueous solutions has been increasing over time, which implies the need for knowledge of the thermodynamic properties of these surfactants. In this study were determined the cloud point of polyethoxylated surfactants from nonilphenolpolietoxylated family (9,5 , 10 , 11, 12 and 13), the family from octilphenolpolietoxylated (10 e 11) and polyethoxylated lauryl alcohol (6 , 7, 8 and 9) varying the degree of ethoxylation. The method used to determine the cloud point was the observation of the turbidity of the solution heating to a ramp of 0.1 ° C / minute and for the pressure studies was used a cell high-pressure maximum ( 300 bar). Through the experimental data of the studied surfactants were used to the Flory - Huggins models, UNIQUAC and NRTL to describe the curves of cloud point, and it was studied the influence of NaCl concentration and pressure of the systems in the cloud point. This last parameter is important for the processes of oil recovery in which surfactant in solution are used in high pressures. While the effect of NaCl allows obtaining cloud points for temperatures closer to the room temperature, it is possible to use in processes without temperature control. The numerical method used to adjust the parameters was the Levenberg - Marquardt. For the model Flory- Huggins parameter settings were determined as enthalpy of the mixing, mixing entropy and the number of aggregations. For the UNIQUAC and NRTL models were adjusted interaction parameters aij using a quadratic dependence with temperature. The parameters obtained had good adjust to the experimental data RSMD < 0.3 %. The results showed that both, ethoxylation degree and pressure increase the cloudy points, whereas the NaCl decrease

How can micelle systems be rebuilt by a heating process?

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Larynx and cervical trachea in humidification and heating of inhaled gases

To evaluate the participation of the larynx and cervical trachea in conditioning inspired gases, we randomly allocated 16 mixed-breed dogs to two groups: group TT (tracheal tube; n = 8) and group LMA (laryngeal mask airway; n = 8). The dogs were anesthetized with pentobarbital sodium and mechanically ventilated for 3 hours. The parameters studied were temperature and absolute humidities of ambient, inhaled, and tracheal air. There was a small increase in tracheal air temperature compared to inhaled air temperature, but no significant difference between groups. The absolute humidity of tracheal air was greater in group LMA than in group TT (23 mg H2O center dot L-1 and 14 mg H2O center dot L-1, respectively; p < .0001). The difference in absolute humidity between the tracheal air and the inhaled air was higher in group LMA at all times (p < .0001). We conclude that the larynx and cervical trachea of the dog participate in humidification and heating of inhaled air by means of air contact with mucosa in this airway segment.

THE INFLUENCE of SHORT-HEATING-CYCLE INVESTMENTS on THE QUALITY of COMMERCIALLY PURE TITANIUM CASTINGS

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Determinação direta e simultânea de Al, As, Fe, Mn e Ni em cachaça por espectrometria de absorção atômica em forno de grafite

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Tungsten permanent chemical modifier with co-injection of Pd(NO3)(2)+Mg(NO3)(2) for direct determination of Pb in vinegar by graphite furnace atomic absorption spectrometry

A tungsten carbide coating on the integrated platform of a transversely heated graphite atomizer (THGA((R))) used together with Pd(NO3)(2) + Mg(NO3)(2) as modifier is proposed for the direct determination of lead in vinegar by graphite furnace atomic absorption spectrometry. The optimized heating program (temperature, ramp time, hold time) of atomizer involved drying stage (110 degrees C, 5 s, 30 s; 130 degrees C, 5 s, 30 s), pyrolysis stage (1000 degrees C, 15 s, 30 s), atomization stage (1800 degrees C, 0 s, 5 s) and clean-out stage (2450 degrees C, I s, 3 s). For 10 mu L of vinegar delivered into the atomizer and calibration using working standard solutions (2.5-20.0 mu g L-1 Pb) in 0.2% (v/v) HNO3, analytical curve with good linear correlation (r = 0.9992) was established. The characteristic mass was 40 pg Pb and the lifetime of the tube was around 730 firings. The limit of detection (LOD) was 0.4 mu g L-1 and the relative standard deviations (n = 12) were typically <8% for a sample containing 25 pg L-1 Pb. Accuracy of the proposed method was checked after direct analysis of 23 vinegar samples. A paired t-test showed that results were in agreement at 95% confidence level with those obtained for acid-digested vinegar samples. The Pb levels varied from 2.8 to 32.4 pg L-1. Accuracy was also checked by means of addition/recovery tests and recovered values varied from 90% to 110%. Additionally, two certified reference materials were analyzed and results were in agreement with certified values at a 95% confidence level. (C) 2006 Elsevier Ltd. All rights reserved.

Effect of modifiers on thermal behaviour of Se in acid digestates and slurries of vegetables by graphite furnace atomic absorption spectrometry

The influence of sample preparation strategy of vegetables on the electrothermal behaviour of Se without and with chemical modifiers such as Pd(NO3)(2), Pd(NO3)(2) + Mg(NO3)(2), Pd(NO3)(2) + Cd(NO3)(2), pre-reduced Pd, Mg(NO3)(2), and Ni(NO3)(2) was investigated. Acid digestates and slurries of vegetables (0.1% m/v in 1% m/v HNO3 + 0.005% v/v of Triton X-100) were used to prepare reference solutions or slurries. For 10 mul of each modifier tested, pyrolysis and atomization temperatures were evaluated using pyrolysis and atomization curves, respectively. Best conditions, such as thermal stability, signal profile, repeatability and sensitivity were attained using Pd(NO3)(2) as chemical modifier. The following heating program (temperature, ramp/hold time) of the graphite tube of the Varian SpectrAA-800Z atomic absorption spectrometer was used: dry step (85 degreesC, 5/0 s; 95 degreesC, 40/0 s; 120 degreesC, 10/.5 s); pyrolysis step (1400 degreesC, 10/3s); atomization step (2200 degreesC, 1/2 s); clean step (2600 degreesC, 2/0 s). This pyrolysis temperature is 800 degreesC higher than when measuring without any modifier. For 20 muL sample volume and 10 mug Pd(NO3)(2), analytical curves in the 3.0-30 mug Se 1(-1) range were obtained. The method was applied for Se determination in acid digestates and slurries of 10 vegetable samples and one standard reference material (rice flower) and results were in agreement at 95% confidence level. Recoveries varied from 89 to 95% for spiked samples. The lifetime of the graphite tube was ca. 250 firings and the relative standard deviations (n = 12) for a typical acid digestate and slurry containing 20 mug Se 1(-1) were 3.8% and 8.3%, respectively. The limits of detection were 2.0 mug Se 1(-1) and 0.6 mug Se 1(-1) Se for digestates and slurries, respectively. (C) 2002 Elsevier B.V. Ltd. All rights reserved.

Determination of selenium in nutritionally relevant foods by graphite furnace atomic absorption spectrometry using arsenic as internal standard

A method has been developed for the direct determination of Se in nutritionally relevant foods by graphite furnace atomic absorption spectrometry. Tungsten/rhodium carbide coating on the integrated platform of a transversely heated graphite atomizer or W coating with co-injection of Pd(NO3)(2) were used as a permanent modifiers. Samples and reference solutions were spiked with 500 mu g L-1 As and absorbance variations due to changes in experimental conditions were minimized. For 20 mu L aqueous analytical solutions delivered into the graphite tube, analytical curves in the 5.0-40 mu g L-1 with good linear correlation were established. Pyrolysis and atomization temperatures were evaluated using pyrolysis and atomization curves, respectively. The optimized heating program (temperature, ramp time, hold time) of the graphite tube of the Perkin-Elmer SIMAA 6000 atomic absorption spectrometer was: dry steps (110 degrees C, 5 s, 10 s; 130 degrees C, 15 s, 15 s); air-assisted pyrolysis step (600 degrees C, 20 s, 40 s; 20 degrees C, 1 s, 40 s); pyrolysis step (1300 degrees C, 10 s, 20 s); atomization step (2100 degrees C, 0 s, 4 s); clean step (2550 degrees C, 1 s, 5 s). The method was applied for Se determination in coconut water, coconut milk, soybean milk, cow milk, tomato juice, mango juice, grape juice and drinking water samples and four standard reference materials and results were in agreement at 95% confidence level. The lifetime of the tube was 500 firings and the relative standard deviations of measurements of typical samples containing 25 mu gL(-1) Se were 3.0% and 6.0% (n = 12) with and without internal standardization, respectively. The limits of detection were in the 0.35 mu g L-1-0.7 mu g Se L-1 range. The accuracy of the proposed method was evaluated by an addition-recovery experiment and all recovered values were in the 98-109% range. (c) 2004 Elsevier Ltd. All rights reserved.

The effect of heating rate on the sintering of agglomerated NaNbO3 powders

The effect of heating rate on the sintering of agglomerated NaNbO3 powders, processed by the polymeric precursors method, was studied. The results showed that the presence of agglomerated powder leads to a heterogeneous microstructure, with bimodal grain size distribution, after sintering. Using a high heating rate, the sintering of agglomerated particles was inhibits, leading to a homogeneous microstructure, with single grain size distribution. (C) 1998 Kluwer Academic Publishers.

Viscoelastic and Thermal Properties of Collagen-Xanthan Gum and Collagen-Maltodextrin Suspensions During Heating and Cooling

The purpose of this work was to investigate the viscoelastic properties of aqueous suspensions of crude collagen powder extracted from bovine hides and nonsubmitted to the hydrolysis reaction that leads to gelatin. The studied variables included the collagen concentration and the addition of xanthan gum or maltodextrin at varied concentrations during heating/cooling of the mixtures. Differential scanning calorimetry thermograms showed that the addition of polysaccharides decreased the endothermic peak areas observed at the denaturation temperature of collagen. The rheological properties of the pure collagen suspensions were highly dependent on concentration: 4% and 6% collagen suspensions presented a great increase in the storage modulus after heating/cooling, whereas for concentrations of 8% and 10% G' decreased during heating and did not recover its original value after heating/cooling. The frequency sweeps showed that the thermal treatment was responsible by the strengthening of the interactions that formed the polymer network. Addition of 0.1% xanthan gum to collagen suspensions increased the gel strength, especially after heating/cooling of the system, whereas increasing gum concentration to 0.3% resulted in a weaker gel, which could indicate thermodynamic incompatibility between the biopolymers. Mixtures of collagen and maltodextrin resulted in more fluid structures than those obtained with pure collagen at the same collagen concentration and the range of temperatures in which these mixtures behaved as a gel decreased with increasing concentrations of both collagen and maltodextrin, suggesting incompatibilities between the biopolymers.