Calibration of the heat exchanger is very important for the device to function efficiently. Factors that people have to consider when it comes to the size of this device: type of heat exchanger, heat carrier characteristics (specific heat, viscosity and density), flow rate and inlet and outlet temperature for each liquid.
When you purchase this type of device, you will usually find that manufacturers provide heat transfer rates in the form of Btu / hour for different temperatures and fluid flow rates. When determining the size, you also need to consider the surface area of the device, as this can also affect the speed and efficiency of the device. Typically, a large surface area can transfer heat faster and more efficiently.
Calculating the size of the heat exchanger can be performed using HYSYS or UniSim. This system can provide you with a temperature chart for both streams versus the amount of heat transferred. But, with this system, it usually gives a heat transfer area of 60.32 meters squared for all heat exchangers, regardless of what is indicated because of its weighted or final design point.
For economic evaluation, you will need to estimate equipment requirements and the area for your entire device, including condensers and reboilers with distillation columns. You also need to use built-in heat exchangers to estimate size and utility requirements.
When calculating heat exchanger dimensions using HYSYS, there are several things you should keep in mind. First, utilities must be higher than one pressure, both incoming and outgoing devices. Two, when steam is used for heating, injected steam should be indicated as all pairs with one vapor fraction, as well as pressure or temperature without an overheated device. Outgoing water should be indicated as a liquid with a vapor fraction of 0 at a pressure just below the inlet pressure. It is not required to indicate the expense.
And when the process steam is cooled by water entering the steam, then the inlet water must be indicated as all liquid with the vapor fraction 0 at a given pressure or temperature or in both. And, the outgoing steam should be indicated as all vapor at a slightly lower pressure.
And, when the flow process is cooled by the refrigerant, then the inlet refrigerant should be indicated as all liquid under high pressure and outgoing refrigerant, since all couples have a much lower pressure. And when cooling water is used, then the specific temperature and pressure, but not steam. You should keep this in mind when calculating with HYSYS or UniSim, because different values will give you inaccurate results. You can also try searching the Internet, as there are websites that will calculate the size of the heat exchanger for you.
