Thermal Engineering Design Project: An Apparatus for Determining the Density of Water in the Neighbourhood of 4°C

Abstract

A thermal engineering design project involving the experimental determination of the density of water in the neighbourhood of 4°C is described in this paper. The author's design employed a sensitive cylindrical float with a diameter of 1.25 mm at the water line. From 0°C to 4°C (water density is maximum at 4°C) the float rose about 8 mm and from 4°C to 25°C the float sank about 40 mm. Using ρ = 1000 kg/m³ at 4°C as a given reference in reducing the data, the density curve closely replicated the curvature of the published density curve. A class of junior mechanical engineering students produced designs using a floating body with varying waterline, a submerged body with varying buoyancy, and a captured body of water rising in a small cross-sectional column. Collectively there were 382 data points. Most of the data clustered very nicely around the published density curve and followed the characteristic hump at 4°C.