Polyvios Eleftheriou

Design and performance characteristics of a parabolic-trough solar-collector system

A comparison of the advantages and disadvantages of concentrating collectors against conventional flat-plate collectors are presented. This is followed by the design of a parabolic-trough solar-collector system, due consideration having been given to collector-aperture and rim-angle optimisation, together with the receiver-diameter selection. The collector characteristic curve gives a test slope of 0·441 and a test intercept equal to 0·642. The value of the test slope differs considerably from the initially predicted value: this is attributed to the heat losses from the receiver support brackets. Subsequent allowance for these losses is presented: this reduces the difference from 24·9% to 5·7%. Other tests are presented, including the determination of the collectors incidence-angle modifier, time constant and acceptance angle.

Industrial noise and its effects on human hearing

Abstract The effects of industrial noise on hearing loss of workers in Cyprus was studied over the period from 1996 to 1999. Measurements of the noise exposure doses of more than 200 workers from 90 Cypriot industries, ranging from timber to food and beverage were evaluated. Audiometric examinations of the studied workers showed that 27.8% suffered some hearing damage while 7.7% suffered serious hearing loss.

Low cost high accuracy parabolic troughs construction and evaluation

This paper describes a low cost method for mass-production of parabolic surfaces with fibreglass. Cavities produced with plastic conduits, covered with fibreglass at the back of the collector surface, provide reinforcement in the longitudinal and transverse directions, to increase rigidity. This produces a low-cost high-rigidity structure that is an accurate copy of the mould. The accuracy of the parabolic surface depends on the accuracy of the mould. The details of the mould production and the procedure for producing the parabolic surface are presented. The total thickness of the fibreglass is 4mm (mean value). The inside surface where the reflector is fixed is manufactured to a high degree of surface finish. The cost of the surface is US

Energy from wastes: a possible alternative energy source for Cyprus' municipalities?

30 per square metre of aperture area for 90° rim angle. The standard deviation of the distribution of the parabolic surface errors is found equal to 4.7 mrad which indicates a very accurate surface. The deflection of the surface to a force corresponding to a wind velocity of 90 MPH is well within reasonable limits.

Solar energy e-learning laboratory - Remote experimentation over the Internet

The net calorific values and weight composition of solid wastes from all the cities of the island of Cyprus were measured. Representative samples were collected and analyzed for heat generation for a complete year. The values appear to vary from city to city, depending on the season and the living habits of the inhabitants. The total energy that could be produced from the waste amounts to approximately 8.5% of the energy produced by combustion of crude oil and subsequent electricity production to satisfy the needs of the whole island nation.