## 3 Experimental Apparatus and Method  
### Experimental Apparatus  
#### 3.1.1 Summary of Experimental Apparatus  
Figure 2 shows the experimental setup of the seawater ice-making device using the scraped surfaced. Figure 3 shows an experimental apparatus actually manufactured. As in Figure 2, the device is largely divided into refrigerant lines, cooling water lines, and seawater lines. The refrigerant side is composed of an inverter scroll compressor, oil separator, condenser, receiver, filter dryer, sight glass, mass flow meter, and scraped surface double tube evaporator. \begin{table}
\begin{tabular}{c c c c c c c c c} \hline \hline \multirow{2}{*}{**Mixing Rate** **(Seawater: Freshwater)**} & \multicolumn{2}{c}{**IFP 0\%**} & \multicolumn{2}{c}{**IFP 10\%**} & \multicolumn{2}{c}{**IFP 20\%**} & \multicolumn{2}{c}{**IFP 30\%**} \\ \cline{2-9}  & **T** & **S** & **T** & **S** & **T** & **S** & **T** & **S** \\  
The high-temperature and high-pressure refrigerant discharged from the compressor are condensed and cooled through a heat exchange with coolant in the condenser, and then it flows into the liquid receiver in the liquid phase. After the receiver, the liquefied refrigerant passes through the filter dryer, the sight glass, and the mass flow meter and the expansion valve. The refrigerant that has passed through the expansion valve flows from the lower portion of the external pipe of the scraped surface double tube evaporator, cools the seawater flowing into the inner pipe, evaporates and flows out to the upper portion of the evaporator. The refrigerant flows to the compressor and it re-circulates. A scraper is inserted into the inner pipe of the evaporator, and it is rotated through the motor at the upper end and scrapes the ice generated from the inner wall to form ice slurry. At this time, the number of revolutions of the scraper were designed to be controlled by the inverter connected to the motor with the scraper. The compressor uses an inverter compressor to adjust the rotational speed according to the set evaporation pressure to maintain a constant evaporation pressure and a water-cooled double tube condenser using corrosion-resistant titanium material is used. The electronic expansion valve controls the refrigerant flow rate by adjusting the opening degree of the expansion valve from 0 to 500 steps so that the superheat degree of the evaporator outlet is kept constant. Since Freon refrigerant is used,  
Figure 3: Photograph of an experiment apparatus. Figure 2: Schematic diagram of an experiment apparatus. an oil separator is installed to facilitate the recovery of oil in the compressor, and for the stability of the system, the receiver and the filter dryer at the outlet of the condenser are installed. The coolant enters the condenser from the coolant tank through the pump, condenses the refrigerant, passes through the flow meter, and returns to the coolant tank. The coolant tank is maintained at a constant temperature through a thermostatic bath. The seawater flowing into the evaporator is also maintained at a constant temperature through a thermostatic bath. Then through a micro-motion gear pump, which can be adjusted to 0.01 LPM, the seawater flows into the evaporator at a constant flow rate and is discharged from the bottom of the evaporator in the form of ice slurry with seawater. As shown in Figure 2, a pressure sensor and T-type thermocouple are installed at the inlet and outlet of the main equipment such as the compressor, condenser, expansion valve, and evaporator to measure the temperature and pressure of the refrigerant. The temperature of seawater and coolant is precisely measured by averaging each three group of T-type thermocouples inserted in tubes and measured up to two decimal places. The flow rates of the refrigerant and coolant are measured through a mass flow meter and a water flow meter, respectively. The power consumed by the compressor is measured using a power meter, and the data logger (YOKOGAWA/GM90 PS) is used for the measurement and recording of all data.