The CNRS-Promes dish∕Stirling system was erected in Jun. 2004 as the last of three country reference units built in the “Envirodish” project. It represents the latest development step of the EuroDish system with many improved components. With a measured peak of 11kW electrical output power, it is also the best performing system so far. The measurement campaign to determine the optical and thermodynamic efficiency of the system is presented. The optical quality of the concentrator and the energy input to the power conversion unit was measured with a classical flux-mapping system using a Lambertian target and a charge coupled device camera system. An efficiency of the concentrator including the intercept losses of 74.4% could be defined for this particular system. For the thermodynamic analysis all the data necessary for a complete energy balance around the Stirling engine were measured or approximated by calculations. For the given ambient conditions during the tests, a Stirling engine efficiency of 39.4% could be measured. The overall efficiency for the conversion of solar to electric energy was 22.5%.

This paper presents a global thermal model of the energy conversion of the 10 kW el Eurodish Dish/Stirling unit erected at the CNRS-PROMES laboratory in Odeillo. Using optical measurements made by DLR, the losses by parabola reflectivity and spillage are calculated. A nodal method is used to calculate the heat losses in the cavity by conduction, convection, reflection and thermal radiation. A thermodynamic analysis of a SOLO Stirling 161 engine is made. The Stirling engine is divided in 32 control-volumes and equations of ideal gas, mass and energy conservation are written for each control-volume. The differential equation system is resolved by an iterative method developed using Matlab™ programming environment. Temperature, mass, density of working gas, heat transfers and the mechanical power are calculated for one Stirling engine cycle of 40 ms and for a constant Direct Normal Irradiation (DNI). The model gives consistent results correctly fitting with experimental measurements.

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Potentiometric titrations showed that the sum of the first three protonation constants of diethylenetriaminepentaacetate N,N"-bis( butylamide) ( L1) decreases by 6.6 units when compared to the diethylenetriaminepentaacetate (dtpa), and that the complexes of Ga3+ and In3+ of L1 have stability constants 6.1 -6.3 log units lower than those of dtpa. The decreased basicity of the bis(amide) derivative thus correlates with the lower stability of its complexes. However, at pH 7.4 the lower overall basicity of L1 compared to dtpa partly compensates the lower stability of its complexes, thus causing their conditional stability constants to be comparable to those of the dtpa complexes. The efficacy of L' in binding Ga3+ and In3+ under physiological conditions is discussed by comparing pM values at pH 7.4, showing that this compound can withstand the competition of transferrin for In3+ in biological media relevant to medical applications. The 13C and l H NMR shifts were measured for the complexes of A13+, Ga3+, In3+ and Y3+ with L1 and compared with 13C shifts for the dtpa complexes. The complexes of A13+ and Ga3+ are hexadentate, possibly of octahedral geometry, and form various structural isomers, whereas those of In3+ and Y3+, with a single structural isomer of eight-co-ordination, are very similar to the lanthanide complexes. The complexes of A13+ and Ga3+ of L1 have considerable populations of isomers with bound amide groups, whereas the single structural isomer of the complexes of In3+ and Y3+ with both amide groups co-ordinated yield a variety of enantiomers in solution. studies on complexes of La3+ and Lu3+ with the corresponding bis(propy1amide) H3L2,22*23 as well as with our studies and literature data on complexes of A13+, G a 3 + , In3+, Y 3 + , La3+ and Lu3+ with dtpa.'9,25*30 ExperimentalReagents.-All chemicals were of analytical grade, used as received unless specifically noted, and obtained from the following sources: diethylenetriaminepentacetic acid dianhydride, pentasodium and di-sodium or -potassium salts of H,dtpa (Sigma); butylamine, aluminium nitrate hydrate, gallium nitrate hydrate, indium nitrate pentahydrate, yttrium chloride (Aldrich); solvents (Prolabo). Other materials are cited under specific sections.Synthesis and Characterization of the N,N "-Bis(buty1amide) of H,dtpa, H3L'.-Butylamine (0.327 cm3, 3 mmol) was added dropwise with stirring to a solution of diethylenetriaminepentaacetic acid dianhydride (0.536 g, 1.5 mmol) in dry dimethylformamide (50 cm3, 40 "C). The colourless reaction mixture was stirred (4OoC, 1 h) and filtered. Chloroform (50 cm3) was added and, after cooling at 4 "C for 2 h, the white solid was filtered off, washed with diethyl ether (100 cm3) and dried at 40 "C overnight. The compound was recrystallized, from hot ethanol-hexane (1 10: 110 cm3), after cooling at 4 "C overnight. The white crystals were filtered off, washed with acetone (10 cm3) and diethyl ether (10 cm3) and dried overnight at 40 "C.

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