Thermal efficiency improvement in high output diesel engines a comparison of a Rankine cycle with turbo-compounding

Thermal management, in particular, heat recovery and utilisation in internal combustion engines result in improved fuel economy, reduced emissions, fast warm up and optimized cylinder head temperatures. turbo-compounding is a heat recovery technique that has been successfully used in medium and large scale engines. Heat recovery to a secondary fluid and expansion is used in large scale engines, such as in power plants in the form of heat recovery steam generators (HRSG) [1]. The present paper presents a thermodynamic analysis of turbo-compounding and heat recovery and utilisation through a fluid power cycle, a technique that is also applicable to medium and small scale engines. In a fluid power cycle, the working fluid is stored in a reservoir and expanded subsequently. The reservoir acts as an energy buffer that improves the overall efficiency, significantly. This paper highlights the relative advantage of exhaust heat secondary power cycles over turbo-compounding with the aid of MATLAB based QSS Toolbox [2] simulation results. Steam has been selected as the working fluid in this work for its superior heat capacity over organic fluids and gases.     

Insights into the cITP process using on-line NMR spectroscopy

Recently, capillary isotachophoresis (cITP) has been coupled on-line with nuclear magnetic resonance (NMR) to enhance analysis of dilute charged analytes through sample concentration and separation. This study focuses on the unique detection capabilities of NMR to noninvasively examine the cITP process and obtain diagnostic information. With their enhanced mass sensitivity, microcoil NMR probes provide optimal detection for cITP/NMR. Whereas previous studies used deuterated buffers, a 1H NMR observable leading electrolyte, tetramethylammonium acetate, is employed here to better track cITP progression. Fortuitously, the 1H chemical shift of the acetate methyl resonance depends on pD. Hence, by using a calibration curve, the solution pD can be determined on-line during cITP. Similarly, intracapillary temperature can be measured in cITP/NMR by observing the HOD chemical shift. To obtain accurate chemical shift measurements, charge-neutral tert-butyl alcohol is added to all cITP electrolyte solutions as an internal reference. As an ancillary benefit, line width measurements of the ubiquitous tert-butyl alcohol enable NMR spectral resolution to be examined throughout the experiment. Capable of providing quantitative results, NMR simultaneously determines the concentrations of the leading ion, sample, and counterion over the course of the cITP experiment.     

Characterization of n-Type and p-Type ZnS Thin Layers Grown by an Electrochemical Method

Electrodeposition of n-type and p-type thin-film layers of ZnS was carried out using a simple two-electrode system and aqueous solutions of ZnCl₂ and (NH₄)₂S₂O₃ with different Zn²⁺ concentrations. X-ray diffraction measurements show that the ZnS layers deposited from both solutions are amorphous. Optical absorption measurements show low absorbance of the layers with energy bandgap in the range of 3.68 eV to 3.78 eV after postdeposition annealing. Photoelectrochemical cell measurements show that both n-type and p-type ZnS thin layers can be electrodeposited by simply changing the concentrations of the deposition solutions. With higher Zn²⁺ concentration in the bath, n-type ZnS films were deposited, while p-type ZnS films were deposited with lower Zn²⁺ concentration. The estimated resistivity of layers from both solutions using I–V measurements were 3.0 × 10⁴ Ω cm and 2.0 × 10⁴ Ω cm, respectively, for n-ZnS and p-ZnS. Scanning electron microscopy shows that the deposited films consist of particles with good surface coverage of the glass/fluorine-doped tin oxide substrate.     

Design of high-efficiency solid-state dye-sensitized solar cells using coupled dye mixtures

A solid-state dye-sensitized solar cell comprising dye mixtures of [Ru(2,2-bpy-4,4′-dicarboxylic acid)(NCS)₂] and [Ru(4,4′,4″-tricarboxy-2,2;6,2″-terpy)(NCS)₃] on TiO₂ thin film was fabricated. The different optical properties of dyes results in increased photocurrent and incident photon to photocurrent efficiency (IPCE). The multiple dye system showed the short circuit current (I_sc) of 10.2 mA/cm² and a cell efficiency (η) of 2.8 while broadening the spectral sensitivity of the cell. When a single dye is used, I_sc of 6 and 5 mA/cm² and cell efficiency of 1.7 and 1.2 were observed for [Ru(4,4-bis(carboxy)-bpy)₂(NCS)₂] (dye 1) and [Ru(2,2′,2″-(COOH)₃-terpy)(NCS)₃] (dye 2), respectively. Additionally, the resulting IPCE for the solar cell consisting of dye mixture was 50% at wide wavelength range from 530 to 650 nm while for the dye 1, 32% IPCE was observed at 535 nm while for the dye 2, highest IPCE value observed was 20% at 620 nm.     

Space-Code CS-CDMA Systems over MISO Frequency-Selective Rayleigh Fading Channels

We propose a transmit diversity CDMA scheme which is a combination of convolutional spreading (CS) and space-time spreading (STS) over multiple-input single-output (MISO) multipath Rayleigh fading channels. With our scheme, multiuser detection over an MISO multipath channel is transformed to single-user detection over a single-input single-output (SISO) multipath channel as the scheme by Petre et al. Because of its simple configuration, it is immediate to see that our scheme realizes full transmit- and path-diversity for two transmit antennas. We extend the system to four transmit antennas employing quasi-orthogonal construction and show a necessary and sufficient condition for full transmit- and path-diversity to be realized. The proposed scheme requires less hardware complexity and less latency than the one by Petre et al.     

Effect of a supplement containing trans-10,cis-12 conjugated linoleic acid on the performance of dairy ewes fed 2 levels of metabolizable protein and at a restricted energy intake

Trans-10,cis-12 conjugated linoleic acid (CLA) inhibits milk fat synthesis in dairy ewes, but the effects under varying dietary metabolizable protein (MP) levels when energy-limited diets are fed have not been examined. The objectives of the study were to evaluate the response of lactating dairy ewes to CLA supplementation when fed diets limited in metabolizable energy (ME) and with either a low or high MP content. Twelve multiparous ewes in early lactation were randomly allocated to 1 of 4 dietary treatments: a high MP (110% of daily MP requirement) or low MP (93% of daily MP requirement) diet unsupplemented or supplemented with a lipid-encapsulated CLA to provide 2.4 g/d of trans-10,cis-12 CLA, in each of 4 periods of 25 d each in a 4×4 Latin square design. All diets were restricted to supply each ewe with 4.6 Mcal of ME/d (equivalent to 75% of ME requirement). Supplementation with CLA decreased milk fat percentage and yield by 33% and 24%, respectively, and increased milk, milk protein, and lactose yields by 16, 13, and 17%, respectively. Feeding the high MP diet increased the yields of milk, fat, protein, and lactose by 18, 15, 19, and 16%, respectively. Milk fat content of trans-10,cis-12 CLA (g/100g) was 0.09 and <0.01 for the CLA-supplemented and unsupplemented ewes, respectively. Ewes supplemented with CLA had a reduced yield (mmol/d) of fatty acids of C16, although the effect was greatest for C16. Plasma urea concentrations were lowest in ewes supplemented with CLA compared with those unsupplemented (6.5 vs. 7.4 mmol/L, respectively) and receiving low compared with high MP diets (5.6 vs. 8.3 mmol/L, respectively). In conclusion, dairy ewes fed energy-limited diets and supplemented with CLA repartitioned nutrients to increase yields of milk, protein, and lactose, with the response to CLA supplementation and additional MP intake being additive.     

Cold isostatic pressing technique for producing highly efficient flexible dye‐sensitised solar cells on plastic substrates

One of the biggest challenges for making dye‐sensitised solar cells (DSCs) on plastic substrates is the difficulty in making good quality nanoporous TiO₂ films with both good mechanical stability and high electrical conductivity. Cold isostatic pressing (CIP) is a powder compaction technique that applies an isostatic pressure to a powder sample in all directions. It is particularly suitable for making thin films on plastic substrates, including non‐flat surfaces. Cold isostatically pressed nanocrystalline TiO₂ electrodes with excellent mechanical robustness were prepared on indium tin oxide (ITO)‐coated polyethylene naphthalate (PEN) substrates in the absence of organic binders and without heat treatment. The morphology and the physical properties of the TiO₂ films prepared by the CIP method were found to be very compatible with requirements for flexible DSCs on plastics. This room‐temperature processing technique has led to an important technical breakthrough in producing high efficiency flexible DSCs. Devices fabricated on ITO/PEN films by this method using standard P‐25 TiO₂ films with a Ru‐complex sensitiser yielded a maximum incident photon‐to‐current conversion efficiency of 72% at the wavelength of 530 nm and showed high conversion efficiencies of 6.3% and 7.4% for incident light intensities of 100 and 15 mW cm⁻², respectively, which are the highest power conversion efficiencies achieved so far for any DSC on a polymer substrate using the widely used, commercially available P‐25 TiO₂ powder. Copyright © 2011 John Wiley & Sons, Ltd.     

Effects of pressurized thermal processing on native proteins of raw skim milk and its concentrate

Heating, pressurization, and shearing can modify native milk proteins. The effects of pressurized heating (0.5 vs. 10 MPa at 75 or 95°C) with shearing (1,000 s^?1) on proteins of raw bovine skim milk (SM, ～9% total solids) and concentrated raw skim milk (CSM, ～22% total solids) was investigated. The effects of evaporative concentration at 55°C and pressurized shearing (10 MPa, 1,000 s^?1) at 20°C were also examined. Evaporative concentration of SM resulted in destabilization of casein micelles and dissociation of α_S1- and β-casein, rendering CSM prone to further reactions. Treatment at 10 MPa and 1,000 s^?1 at 20°C caused substantial dissociation of α_S1- and β-casein in SM and CSM, with some dissociated caseins forming shear-induced soluble aggregates in CSM. The pressure applied at 10 MPa induced compression of the micelles and their dissociation in SM and CSM at 75 or 95°C, resulting in reduction of the micelle size. However, 10 MPa did not alter the mineral balance or whey proteins denaturation largely, except by reduction of some β-sheets and α-helices, due to heat-induced conformational changes at 75 and 95°C.     

Fully Roll-to-Roll Processed Efficient Perovskite Solar Cells via Precise Control on the Morphology of PbI2∶CsI Layer

Perovskite solar cells(PSCs)have attracted tremendous attention as a promising alternative candidate for clean energy genera-tion.Many attempts have been made w...