Cooper H. Langford

SOLAR ENERGY STORAGE USING CHEMICAL POTENTIAL CHANGES ASSOCIATED WITH DRYING OF ZEOLITES

Abstract Compact solar storage systems depend upon identification of systems which can store energy as chemical potential. Simple, noncorrosive, systems that operate at reasonably low temperatures are rare. The use of the heat of adsorption of moisture on zeolite molecular sieves is discussed here. The advantages of zeolites are high heats of adsorption (as much as 80 kJ mol−1), large maximum adsorption capacity (0.2–0.3 kg H2O/kg adsorbent) and easy control of the store following from control of heat output by regulations of flows of moist air. The disadvantages are the relatively high upper temperature required to utilize maximal storage capacities (up to 250°C) and cost. There is reason to project falling cost. Zeolite storage is compared favourably with respect to capacity to water, stone, and heat of phase change systems. Compared to salt hydrates, acid solution, and salt solutions any capacity advantage is supplemented by low corrosion and opportunity for long term storage. Zeolites are compared favourably to alternative absorbent materials; alumina, charcoal, and silica gel. The warm dry air output from a zeolite storage bed can be utilized not only in space heating but also in the drying of agricultural timber and fish products.

THE RATES OF SOLAR ENERGY STORAGE AND RETRIEVAL IN A ZEOLITE-WATER SYSTEM

Abstract The salient features that determine the possible use of a water vapour-zeolite 13X system as a method of energy storage were investigated. Cycling studies over two months revealed no decrease in water capacity nor any structural deterioration. The rate at which water could be desorbed in a static situation was determined at various temperatures from 110 to 250°C. The adsorption isotherm and the heats of adsorption as a function of amount of adsorbed water were determined. The saturation capacity was 0.33 g H2O/g zeolite while the heat of adsorption declined from 90 to 50 kJ mol−1. The rate of heat development was found to be very high so that heat extraction from the store would not be a problem in any practical utilization of this system.

Kinetic Analysis Applied to Iron in a Natural Water Model Containing Ions, Organic Complexes, Colloids, and Particles

Abstract Kinetic analysis using complex formation reactions is applied to “mixtures” containing (variously), Fe3+, Fe2+, iron complexed to a fulvic acid, hydrous oxide colloids, and non-settleable particulate iron. Such mixtures can be directly resolved if the kinetics of complex formation reactions are pseudo first order and differences among rate constants are large enough. At pH = 4, it is found that fulvic acid causes substantial reduction of Fe3+ to Fe2+ and that it causes complete dissolution and depolymerization of colloidal and particulate iron at 1:1 ratio. Addition of one equivalent of phosphate causes precipitation of ferric phosphate even in the presence of fulvic acid. This system is very useful for modeling natural water because the kinetic technique allows convenient analysis of components of varying particle size. The present results are strongly indicative of the role of fulvic acid in mediating metal ion chemistry in natural water.

Preferential solvation in kinetics

Abstract An approach to solvent effects in kinetics of reactions slower than diffusion control is considered based on the partition of the reaction into an encounter equilibrium and a first order rate process for rearrangement of the encounter complex. Solvent effects are partitioned into those relating to encounter equilibria and those relating to the rate process. The distribution of solvent molecules at equilibrium is discussed in terms of NMR derived preferential solvation data and complex formation reactions of various Cr(III) and Ni(II) species are used as specific illustrations.

Paper recycling energetics: some Canadian experience.

Abstract Energy calculations for manufacture of paper from logs and waste papers are reported based on data on energy use from the Canadian Census of Manufactures and estimates for collection and de-inking of waste. The energy requirement of the recycling technology explored exceeds the energy requirement of manufacture from logs by 33%. It appears that forest conservation through recycling has a fossil fuel cost.