## 3 Numerical Findings  
### Effect of Oblique Obstacle Placement on Temperature Distribution in Tank for Different Flow Rates  
Using the temperature distribution in the tank to assess the thermal performance of a hot water tank is a basic, simple, and fast method. This is because the temperature of the water in the tank and the amount of stored hot water is directly shown. It is desirable to store water at the highest temperature and volume as possible in a hot water storage tank. The temperature distribution in the tank offers this information directly. At the end of the test period of 120 min, the temperature distribution for the oblique obstacle placement tank is shown in Figures 5-11, at a different velocity for each model. As can be seen in successive figures; the increase in the storage tank inlet velocity (V\({}_{\text{main}}\)) has reduced the domestic water outlet temperature. As a result, considering the temperature distribution in the tank after 120 min, increasing the input velocity negatively affects the temperature distribution within the tank. Figure 5: Temperature distributions for normal (not obstacle) V\({}_{\text{mantle}}\) = 0.147 m/s (**a**) V\({}_{\text{main}}\) = 0.036 m/s, (**b**) V\({}_{\text{main}}\) = 0.073 m/s, (**c**) V\({}_{\text{main}}\) = 0.11 m/s, (**d**) V\({}_{\text{main}}\) = 0.147 m/s. Figure 7: Temperature distributions for a = 60\({}^{\circ}\), m = 50 mm, l = 200 mm, V mantle = 0.147 m/s, (a) V\({}_{\rm main}\) = 0.036 m/s, (b) V\({}_{\rm main}\) = 0.073 m/s, (c) V\({}_{\rm main}\) = 0.11 m/s, (d) V\({}_{\rm main}\) = 0.147 m/s. Figure 10: Temperature distributions for a = 60\({}^{\circ}\), m = 150 mm, 1 = 100 mm, V\({}_{\rm mantle}\) = 0.147 m/s, (a) V\({}_{\rm main}\) = 0.036 m/s, (b) V\({}_{\rm main}\) = 0.073 m/s, (c) V\({}_{\rm main}\) = 0.11 m/s, (d) V\({}_{\rm main}\) = 0.147 m/s. Effect of Oblique Obstacle Placement on the Average Storage Water Temperature in Tank for Different Flow Rates  
The average temperature of the water storage in a hot water tank is quite critical, and it is desirable for the temperature of the storage water to be at the highest level. Change over time of the average storage temperature water for all cases is given in Figure 12. Even though it does not give information about the amount of hot water alone, the distribution of the temperature within the tank and the evaluation of the system performance also provides important information. In Figures 5-11, the variation in the temperature of the hot water stored in the tank over time is seen for all cases. With the exception of V = 0.036 m/s, the water temperature stored at lower velocity is generally higher. If the temperatures in Figures 5-11 are compared with the findings obtained from the distribution, using the oblique obstacle, positioning this oblique at the position of m = 100 mm from the mains input and keeping the velocity at V = 0.073 m/s provides the highest amount of water storage in the tank. Both the system's thermal energy storage performance and user satisfaction will increase with the use of obstacles under the specified conditions. Effect of Oblique Obstacle Placement on the Mantle Outlet and Main Outlet Temperature in Tank for Different Flow Rates  
Mantle outlet temperature and mains outlet temperature are important performance parameters for mantle hot water tanks. The mantle outlet temperature is important for the thermal efficiency of the hot water tank and the collector. The low mantle output temperature increases the efficiency of the mantle heat exchanger and collectors. In addition, higher temperature changes will change the density of the water and increase the speed of natural circulation. For these reasons, it is generally desirable for the mantle exit temperature to be at the lowest possible level. The usage water outlet temperature is directly related to user satisfaction. Users want hot water at the highest possible temperature and quantity. Figure 12: Change over time of the average storage temperature water for all cases.