Reduced operating temperatures

Lang M, Franco T, Schiller G, and Wagner N. Electrochemical characterization of vacuum plasma sprayed thin-film solid oxide fuel cells (SOFC) for reduced operating temperatures. J. Appl. Electrochem. 2002 32 871-874. 

Improved thermodynamic or kinetic efficiencies of reactors by design upgrades (e.g., improved mixing or heat transfer) to reduce operating temperatures and/or pressures... 

Operating the column at the minimum pressure minimizes the energy cost of separation. Towering this pressure increases the relative volatility of distillation components and thereby increases the capacity of the reboiler by reducing operating temperature, which also results in reduced fouling. Reducing pressure also affects other parameters, such as tray efficiencies and latent heats of vaporization. 

Horita, T. et al.. Evaluation of Fe-Cr alloys as interconnects for reduced operation temperature SOFCs,/. Electrochem. Soc., 150, A243-A248 (2003). 

Reduce operating temperature to improve life and performance. 

Cell design is also an important factor to improve the performance of SOFC stack/module [15-18]. Use of small diameter SOFC may also give opportunity to reduce operating temperature by increasing the volumetric power density [19]. Thus, they are expected to accelerate the progress of SOFC systems which can be applied to portable devices and auxiliary power units for automobile. 

In contrast to stationary applications, portable applications require frequent start and stop procedures. Therefore for SOFC, a robust cell design and adapted electrode-electrolyte assemblies are an important issue. Frequent thermal cycles between room temperature and an operation temperature of about 600-800 °C pose challenges to the layered system consisting of solid anode, ceranfic electrolyte and solid cathode with respect to thermal and mechanical stability. For several years, different approaches to developing tubular nficro SOFC have been undertaken but did not lead to a commercial product yet. As SOFC can be operated with pure hydrogen, reformate and hydrocarbons as fuel as well - the latter option means direct internal reforming at the anode catalyst — various investigations focused on reduced operation temperature and a parallel conversion of fuels [21]. 

The case studies analysis, which focused on hydrogen production processes, demonstrates the potential of membrane reactor technology in terms of improving performance and reducing operating temperature, even if some crucial obstacles have yet to be overcome, as developing a reliable fabrication method and reducing membrane costs. 

Another desirable optical characteristic for the encapsulant would be rejection of infrared (IR) sunlight of wavelengths longer than usable by the solar cells. The rejection of the infrared sunlight would raise module performance and increase module lifetime by reducing operating temperatures. However, a cost-effective method for rejecting the infrared heat has not been developed. 

M. Lang, T. Franco, G. Schiller, and N. Wagner [2002] Electrochemical Characterization of Vacuum Plasma Sprayed Thin-Film Solid Oxide Fuel Cells (SOFC) for Reduced Operating Temperatures, J. Appl. Electrochem. 32, 871-874. 

G. Schiller, R. H. Henne, M. Lang, R. Ruckdaschel, and S. Schaper [2000] Development of Vacuum Plasma Sprayed Thin-FUm SOFC for Reduced Operating Temperature, Euel Cells Bulletin 21, 7-12. 

Colloidal fabrication and co-sintering processes have emerged, whereby YSZ membranes are produced as thin films ( 10 pm) on porous electrode structures. These thin-film membranes improve performance and reduce operating temperatures of SOFCs. To enable these colloidal processes to be successful, finer YSZ powders are needed. These applications require nano-scale powders with BET surface areas of 100 to 120 mVg and the use of suspensions ranging from 10 to 40 percent solid content (7, 8). 

Pfeifer T, Nousch L, lieftink D, Modena S (2013) System design and process layout for a SOFC micro-CHP unit with reduced operating temperatures. Int J Hydrogen Energy 38 431 39... 

This type of portable heater consists of a porous film that prevents the movement of heating components by keeping them in a sheet form on one side. On the other side of the sheet is an adhesive by which the disposable heater is adhered to the clothing. This allows close contact to the body and a reduction of thickness, which results in energy saving due to low-temperature operation, preservation of resources and the reduction of waste. Improved ease of use and safety by reduced operating temperature were well received by consumers, who also were attracted by the widened options for placement of the heaters on the body. 

Union Carbide Corporation was working on a low-pressure hydroformylation process as early as 1967, and used a rhodium carbonyl catalyst modified with a triphenyl phosphine ligand. " The ligand dramatically improved the normal/iso-aldehyde ratio of the product when compared to the free metal carbonyl. Reduced operating temperatures and pressures, low by-product formation, and the elimination of metallic rhodium deposition were also achieved. By 1975, a plant was operating using this catalyst, and the process was being licensed for the hydroformylation of propylene. 

Besides manufacturing and economic issues, the main technical limitations of the SOFC include achieving a reduced operating temperature, controling start-up time, durability, and proper cell-sealing. The SOFC is discussed in depth in Chapter 7. 

---