Question

Solve Q1 and Q2 by matlab :

Q1: Based on what you learned about thermophysical

properties library, calculate the density of seawater at 25°C

and Pressure 1 MPa where the salinity is changed from 25,000

ppm to 55,000 ppm ?

02: Based on what you learned about thermophysical

properties library, calculate the density of seawater at

Pressure 1 MPa and has salinity of 42,000 ppm where the

temperature is changed from 25°C to 65°C ? If it changed why?

Answer 1

The density of pure water is 1000kg/m³. Ocean water is dense because of the salt.

Density of ocean water at the sea surface is about 1027 kg/m³. There are two main factors that make ocean water more or less dense than about 1027 kg/m³. The first is the temperature of the water and the other us the salinity of the water.

However, temperature has a greater effect on the density of water than does salinity. Hence, a layer of water (pycnocline) with higher salinity can actual float on top of water with lower salinity if the layer with higher salinity is quite a bit warmer than the lower salinity layer.

The density of ocean water increases somewhat proportionately as you go to or toward the bottom of the ocean. The deep ocean is layered with the most dense water on bottom and the lightest water on top. Circulation in the depths of the ocean is horizontal, a result of deviations in density in constrast to surface circulation which is a product of surface winds.

i.) For ocean water at 25⁰C, 1MPa and 25000ppm of salinity the density is 1015.833kg/m³ .

For ocean water at 25⁰C, 1MPa and 55000ppm of salinity the density is 1038.58kg/m³ .

ii.)  For ocean water at 25⁰C, 1MPa and 42000ppm of salinity the density is 1028.671kg/m³ .

  For ocean water at 65⁰C, 1MPa and 42000ppm of salinity the density is 1011.293kg/m³ .

The results indicate that, When the water is heated, it expands, increasing in volume. The warmer the water, the more space it takes up, and the lower its density. When comparing two samples of water with the same salinity, or mass, the water sample with the higher temperature will have a greater volume, and it will therefore be less dense.