Seawater Pump Research Articles

Optimization of an ocean thermal energy conversion system

Abstract The optimum performance of a simple Rankine cycle ocean thermal energy conversion plant is investigated analytically. It is shown that the ratio of maximum net power output to heat exchanger surface area varies as H(Δt − t 0 ) 2 where H describes the overall heat transfer properties of the evaporator and condenser, Δt is the temperature difference between the warm and cold sea water supplies, and t 0 is a parameter depending primarily upon the pressure drops across the warm and cold sea water pumping systems. The model is relatively insensitive to the choice of working fluid, although ammonia is used as the illustrative example.

Ultrastructural Observations on Nanoplankton Collected from the Coast of Jugoslavia and the Bay of Algiers

A large number of nanoplankton species originally found in the sea around Britain have now been collected from other northern temperate waters (see Leadbeater, 1972 c; Manton & Leadbeater, 1974). It was, therefore, of considerable interest to collect nano-plankton from warmer waters such as those of the Adriatic and Mediterranean. The larger plankton of both the Adriatic and Mediterranean has been the subject of investigation by a succession of scientists from many countries (for references see Tregouboff, 1952). Whilst many workers acknowledged the importance of the smaller plankton from these areas (e.g. Bernard, 1958; Lalami-Taleb, 1971) only a few have attempted to study and identify species belonging to this group. In this respect the meticulous work of Lohmann (1902a, 1911) and Schiller (19136, 19256) requires special mention. Lohmann (1902a), working on the phytoplankton from the coast of Sicily, first used the technique of pumping sea water through filter paper and in this way he was able to collect and identify many minute species for which he later suggested the name ‘ Nannoplankton’ (Lohmann, 1911). On a later excursion to the Atlantic Ocean, Lohmann (1911) found the gentle centrifugation of sea-water samples was a more satisfactory and less destructive way of concentrating small cells. Schiller's most important contribution concerns a phytoplankton study carried out as part of an international hydrobiological survey of the Adriatic Sea during the years 1911–14. Schiller's findings confirmed many of Lohmann's previous observations and added a further range of new species including many green flagellates (Schiller, 1913 6, 1925b).

The use of potentiostatic techniques in the development of improved stainless steels for chemical plant

AbstractIt is possible by potentiostatic methods to exactly forecast the behaviour of unusual material/corrodent systems; such methods may, consequently, be used for the development of corrosion resistant alloys. A new alloy on iron base (with, %, 25 Cr, 5.5 Ni, 3.0 Cu, 2.5 Mo) combines very good mechanical properties with resistance to general corrosion, pitting and crevice corrosion. Industrial applications include impellers for pumps operating in acid slurries (30% P2O5, 30% CaSO4 as solids, 2% H2SO4, HF, H2SiF6; 60–80°C, three years without corrosion); pump impeller for sulfuric acid and other corrosive products shipped in tank ships; impeller for a sea water pump (no corrosion after 4 years' operation).

Micro-zooplankton and its abundance relative to the larger zooplankton and other seston components

Micro-zooplankton populations in the upper 100 m were sampled from 5 marine environments in the northeast Pacific Ocean extending from slope waters off San Diego to an oceanic site near Isla Guadalupe, and their abundance related to that of the larger zooplankton, phytoplankton (as estimated from chlorophyll a), and detritus. The micro-zooplankton and other components of the seston were subdivided into 3 fractions on the basis of size in the deck-mounted collecting unit of a seawater pumping system. Through the euphotic zone at each site, the Protozoa, of which ciliates were the dominant forms, accounted for 95% or more of the total micro-zooplankton numbers. Their biomass, as volume, was estimated to be 13 to 28% of that of the total micro-zooplankton. The standing stock of micro-zooplankton over the euphotic zone at the various sites, in terms of dry weight, was estimated to be 14 to 34% (average 23%) of that of the phytoplankton crop. Micro-zooplankton volumes in the upper 100 m were 21 to 26% of those for the larger zooplankton sampled over the same depth.