🔍 Key Concepts

• Heat transfer in heat exchangers (conduction through the tube walls and convection on both fluid sides) • The basic heat transfer relationship: heat rate depends on temperature difference, heat transfer area, and overall heat transfer coefficient • How flow rate affects the temperature difference and heat transfer coefficient on both the hydraulic and water sides

💭 Think About

• In a shell-and-tube cooler, think about which factors actually change how much heat moves from the hot fluid to the cold fluid, not just how hot or cold one side starts out. • Ask yourself: if you changed only the flow rate, with everything else the same, would the heat transfer change? What if you changed only the hot fluid temperature? Only the cooling water temperature? • Consider whether heat transfer depends on a single variable alone, or on a combination of variables working together in the exchanger.

✅ Before You Answer

• Review the basic formula for heat transfer: Q ∝ U × A × ΔT and how ΔT is influenced by both hot and cold fluid temperatures. • Think about how increasing flow rate on either side normally affects the outlet temperatures and the overall heat transfer rate. • Check whether any option that lists only one variable is missing other clearly important factors that also influence heat transfer.