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A pragmatic approach to estimate the impact of climate change on the urban environment, here called the cuboid method, is presented. This method allows one to simulate the urban heat load and the frequency of air temperature threshold exceedances using only eight microscale urban climate simulations for each relevant wind direction and time series of daily meteorological parameters either from observations or regional climate projections. Eight representative simulations are designed to encompass all major potential urban heat-stress conditions. From these representative simulations, the urban-heat-load conditions in any weather situation are derived by interpolation. The presented approach is applied to study possible future heat load in Frankfurt, Germany, using the high-resolution Microscale Urban Climate Model in three dimensions (MUKLIMO_3). To estimate future changes in heat-load-related climate indices in Frankfurt, climate projections from the regional climate models Max Planck Institute Regional Model (REMO), Climate Limited-Area Model (CLM), Wetterlagen-basierte Regionalisierungsmethode (WETTREG), and Statistical Regional Model (STAR) are used. These regional climate models are driven by the ''ECHAM5'' general circulation model and Intergovernmental Panel on Climate Change emission scenario A1B. For the mean annual number of days with a maximum daily temperature exceeding 258C, a comparison between the cuboid method results from observed and projected regional climate time series of the period 1971-2000 shows good agreement, except for CLM for which a clear underestimation is found. On the basis of the 90% significance level of all four regional climate models, the mean annual number of days with a maximum daily temperature exceeding 258C in Frankfurt is expected to increase by 5-32 days for 2021-50 as compared with 1971-2000.

For calculation of phase equilibria of the system seed oil/CO2, an equation of state published in the literature has been fitted to experimental data of that system. The results thus obtained are of only limited use in designing a supercritical extraction process. The experimental investigation of the mass transfer kinetics is much more significant. Mechanical processing of the oil seed's cell wall structure has been shown to be of great importance. The best specific yields were achieved with material that had been mechanically pre‐deoiled and thereby broken open. Yields are increased considerably by use of the gas mixture CO2/propane or other special gas mixtures or by the addition of refrigerants. However, the extraction times achieved in batch operation, together with the mass product nature of oil seed, make a continuous supercritical extraction essential if operation is to become economic relative to the conventional hexane extraction. To this end, the energetics of the process have been calculated, and practical possibilities for continuous operation are discussed.

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A one-dimensional soil-vegetation model is developed for future incorporation into a mesoscale model. The interaction of land surface processes with the overlying atmosphere is treated in terms of three coupled balance equations describing the energy and moisture transfer at the ground and the energy state of the vegetation layer. For a complete description of the interaction, the coupled processes of heat and moisture transport within the soil are included as a multilayer soil model. As model verification, successful reproductions of the observed energy fluxes over vegetated surfaces from the HAEEX-MOBILHY experiment in southwestern France and from the LOTREX-lOE/HIBE88 field experiment in Germany are presented. Finally, some sensitivity studies are performed and discussed in order to investigate the influence of different soil and vegetation types on the energy state of the atmosphere.

A numerical scheme is described for the calculation of effective albedo values of long city street canyons. The method is based on a generalization of the radiation model for inclined surfaces recently presented by Briihl and Zdunkowski (1983). Calculated albedo values are compared with Aida's (1982) experimentally determined results. It is found that experiment and theory are in reasonable and in some cases in excellent agreement. Additional results obtained by varying the geometry of the street canyon as well as the surface reflectivities are shown to demonstrate the versatility of the calculation scheme.

Supercritical fluid extraction in large-scale industrial plants has concentrated upon natural materials, e.g. coffee, tea, hops and tobacco, and is being extended towards specialities which would require smaller production plants. Process engineering aims at improved scale-up from experimental to production scale and at improved economic viability, e.g. by saving energy and by continous transport of solids through pressure vessels. Equipment design investigations are concerned with closure systems and the relevance of pressure release and solvent recovery for the design of pressure vessels.The present state and the developmental trends concerning the extraction of natural materials with supercritical fluids may be described under the following aspects:The large-scale plants which have so far been realized for the decaffeination of tea and coffee and for the extraction of hops and spices are now established. These are in general one-stage plants in which the extract is separated by adsorption on activated carbon or by pressure reduction. The tendency now is to replace adsorption by absorption in washing towers. As an example, the annual production of 20,000 t/a coffee with activated carbon caffeine separation involves the loss of more than 200 t of caffeine, since this potential by-product is destroyed during the thermal regeneration of the adsorbent. The questions of energy-saving and of the economic recovery of CO 2 are also of interest for large-scale plants which already exist or which are still to be designed.Investigations on laboratory and pilot-plant scale have already been performed with many natural products.

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