Design of counter flow, concentric heat exchanger Problem Statement The task is to design a double-pipe, counter flow heat exchanger as shown in Figure 1. The heat exchanger is used to cool the engine oil for a large industrial gas turbine engine. The flow rate of cooling water through the inner tube is A kg/s= 0.3, while the flow rate of oil through the outer annulus is B kg/s= 0.02. The water and oil enter the inner tube and outer annulus at temperatures of D = 30 degree Celsius and C = 150 degree Celsius respectively. The wall thickness of the water tube is 2 mm. You have to find an optimum design of the heat exchanger in terms of high performance and low cost, and ensure that the outlet temperature of the oil does not exceed 60 degree Celsius. As shown in the figure, three bends of the heat exchanger must be located outside the steel shell and you have to take into account the convective heat transfer from the tube to the ambient air for these three regions. You need to validate your design by showing that there is no effect of mesh on solution results. (Select refined mesh size at your own discretion). Figure 1 Double-pipe, counter flow heat exchanger. Fig 1 Design Requirements and Constraints 1. The heat exchanger model must be three-dimensional 2. Water tube inner diameter should not be more than 40mm 3. Annulus inner diameter should not be more than 80mm 4. The length of each water tube measured horizontally from flange to flange should not exceed 2 meters. 5. Structured mesh must be used 6. In your CFD model you can neglect flanges