Thermodynamic and heat transfer analysis of heat recovery from engine test cell by Organic Rankine Cycle

During manufacture of engines, evaluation of engine performance is essential. This is accomplished in test cells. During the test, a significant portion of heat energy released by the fuel is wasted. In this study, in order to recover these heat losses, Organic Rankine Cycle (ORC) is recommended. The study has been conducted assuming the diesel oil to be composed of a single hydrocarbon such as C₁₂H₂₆. The composition of exhaust gases (products of combustion) have been computed (and not determined experimentally) from the stoichiometric equation representing the combustion reaction. The test cell heat losses are recovered in three separate heat exchangers (preheater, evaporator and superheater). These heat exchangers are separately designed, and the whole system is analyzed from energy and exergy viewpoints. Finally, a parametric study is performed to investigate the effect of different variables on the system performance characteristics such as the ORC net power, heat exchangers effectiveness, the first law efficiency, exergy destruction and heat transfer surfaces. The results of the study show that by utilizing ORC, heat recovery equivalent to 8.85 % of the engine power is possible. The evaporator has the highest exergy destruction rate, while the pump has the lowest among the system components. Heat transfer surfaces are calculated to be 173.6, 58.7, and 11.87 m² for the preheater, evaporator and superheater, respectively.     

Inverse-voltammetric determination of cadmium, lead and copper in animal samples after solubilization

Summary The conditions for the inverse-voltammetric determination of cadmium, lead, and copper in various biological samples after solubilization with Texapon are described. The results of this procedure are compared with those obtained with conventional high- and low-pressure wet digestions. The advantages of the Hg-film electrode as compared to the stationary Hg-electrode are discussed.Dedicated to Prof. Dr. G. Schulze on the occasion of his 60th birthday Permanent address: Technical University of Poznan, Institute of Chemistry, Poznan, Poland     

Invers-voltammetrische Bestimmung einiger Schwermetalle in Bier durch Kombination eines UV-Aufschlusses mit Durchflu?zelle

Summary The inverse-voltammetric determination of the natural contents of lead and copper in beer is possible in a flow-through cell with medium exchange after UV-photolysis. The working conditions are given and the results are compared with those obtained by a wet oxidative digestion procedure. The relative standard deviations were: Cu 3.5% and Pb 1.4%.

---

---

Herrn Prof. Dr. G. Tölg zum 60. Geburtstag     

Direct inverse voltammetric determination of Pb, Cu and Cd in some edible oils after solubilization

The direct determination of traces of certain heavy metals in oils is possible after treatment of the methanolic sample solution with Lumatom (tetramethylammoniumhydroxide). For the inverse voltammetric determination, a flow through cell with a mercury film electrode is used. The results for the determination of Cu and Pb in some edible oils after solubilization agree well with those obtained using wet oxidative high pressure ashing.     

Adsorptionsvoltammetrische Bestimmung des Cobalts und Nickels an Quecksilberfilmelektroden und in Durchflu?zellen

Zusammenfassung Die adsorptionsvoltammetrische Bestimmung des Cobalts und Nickels an einer mit einem Hg-Film überzogenen Glascarbonelektrode und in Durchflußzellen wurde untersucht. Absolute Mengen von 0,1 ng Co und 0,5 ng Ni können in einer derartigen Zelle mit großer Analysengeschwindigkeit bestimmt werden (22–25 s pro Bestimmung).

---

Determination of cobalt and nickel by adsorption voltammetry at mercury film electrodes and in a flow-through cell

Summary The determination of cobalt and nickel by adsorption voltammetry at a mercury plated glassy carbon electrode and in flow-through cells has been investigated. Absolute amounts of 0.1 ng Co and 0.5 ng Ni can be determined in such cells with high speed of analysis (22–25 s per determination).

---

---

Die Untersuchungen wurden in dankenswerter Weise durch Mittel der Deutschen Forschungsgemeinschaft und des Verbands der Chemischen Industrie — Fonds der Chemischen Industrie — unterstützt.     

o-Phenylenediamine as a New Catalyst in the Highly Regioselective Conversion of Epoxides to Halohydrins with Elemental Halogens

The regioselective ring opening of epoxides using elemental iodine and bromine in the presence of o-phenylenediamine as a new catalyst affords vicinal iodo alcohols and bromo alcohols in high yields. The major advantages of this method are versatility, high regioselectivity, a cheap and commercially available catalyst, mild and neutral reaction conditions, and short reaction times. Fourier transform Raman spectroscopy was used to study the reaction of iodine with o-phenylenediamine. The results indicate that the complex [(Diamine)I]⁺·I₅^– is formed, and we suggest that the major nucleophile is the pentaiodide ion. This bulky nucleophile has a fundamental role in the high regioselectivity observed attacking the less sterically hindered epoxide carbon.     

Zur inversvoltammetrischen Bestimmung des Zinks in saurer L?sung (Anodische Amalgamvoltammetrie XIII)

Zusammenfassung Zur Bestimmung kleiner Zinkmengen in salzsauren Lösungen ist die inverse Wechselspannungsvoltammetrie geeignet. Besonderheiten des Einflusses der Elektrolysezeit und kleinerer Kupfergehalte werden beschrieben. Die Standardabweichung der Einzelbestimmung mit 50 ng Zn/ml betrug ± 1,6%.

---

On the inverse-voltammetric determination of zinc in acidic solution

Summary Small amounts of zinc can be determined in hydrochloric acid solutions by a.c. voltammetry. Special influence of electrolysis time and copper interference are reported. In case of single determinations with 50 ng Zn/ml the standard deviations were ± 1.6%.

Die Untersuchungen wurden in dankenswerter Weise durch Mittel der Deutschen Forschungsgemeinschaft und des Verbandes der Chemischen Industrie unterstützt.     

A two-dimensional potential function for bent hydrogen bonded systems. II-6-hydroxy-2-formylfulvene

A simple and practical method for treating the non-adiabatic proton tunneling in 6-hydroxy-2-formylfulvene was used. A two dimensional potential energy surface function, which couples OH stretching and in-plane bending modes, has been constructed for motion of hydrogen by the aid of quantum mechanical calculations at MP2/6-31G** level for a fixed skeleton geometry. This potential was used for calculation of energy levels from which a tunneling splitting of 181±14 cm⁻¹ was obtained in an excellent agreement with the experimental value of at least 150 cm⁻¹. The calculated barrier height for these results was about 26–27 kJ/mol. This method also assigns a broad band at about 1740 cm⁻¹ to the OH in-plane bending mode. The calculated hydrogen bond strength was estimated to be about 80 kJ/mol.