- To investigate the melting stage of indirect freeze desalination three numerical models were developed. A zeroth, ﬁrst, and second order analyses modeled the melting of ice around the outside of a pipe as a function of time. The zeroth order analysis assumes the system to be steady state. The ﬁrst order analysis allows for variations in time and assumes the temperature proﬁle along the pipe to be linear. The second order analysis allows for variations in time and space and considers the full length of the pipe. These models use water as the working (heating) ﬂuid and were run at a base case consisting of inlet temperature of 293 K, mass ﬂow rate of 0.1 kg/s, pipe inner radius of 3.85 mm and pipe outer radius of 4.95 mm. The eﬀect of varying parameters on the output volume of water was investigated by running the second order analysis, changing one parameter at a time relative to the base case conditions. Increases in inlet temperature and mass M. G. Pratt ﬂow rate yielded increases in output volume. Increasing mass ﬂow rate above 0.1 kg/s had no beneﬁt on the output volume. Decreases in inner and outer pipe radii resulted in additional output volume. Smaller pipe radii worked better because many small pipes have more surface area than fewer large pipes. Using the second order analysis with a similar analysis of the freezing stage, the optimal cycle time of 68.2 minutes was found to produce 12.3 liters of fresh water per tube per day at the cost of 22.5 kWh/liter.
- Key Words: Desalination, Freezing, Indirect, Melting