Question

Problem 1: MSH 5-like: You are making chocolate candies and need transport the melted chocolate via a tube a short distance to the work table. You have been asked to design the tubing size (inner diameter, D), such that the flow rate does not exceed what a person can easily work (20 mL/s). The tubing needs to be 2.0 m long and can assumed to be smooth. A pinch valve will be installed, which can be used to restrict flow; however, does not contribute a friction factor when open. A pressurized tank will be used to provide the energy to move the chocolate. The pressure in the tank is 250 kPa gauge. One could assume the change in height of chocolate in the tank (H) with time is negligible (i.e., the change in potential energy with time relative to the work due to the pressure flow). The density of the chocolate at the temperature in the tank is 1350 kg/m and it has a Newtonian apparent viscosity of 32 CP (0.032 kg/m:s) at this temperature). Assume the tubing is well-insulated, such that the chocolate remains at a constant temperature while in the tubing. Clearly define your system. State any assumptions. - P 250 KP. Ches 48°C : 2.0m large tank ? A) What is the work flow term (AWPF) in the energy balance (include units)? B) What is the kinetic energy term (Ek) in the energy balance (include units)? Name: Student ID: Problem 1 con't C) What is the potential energy term (AEP) in the energy balance include units)? D) What is the diameter of the tubing (m) needed to deliver the desired flow rate ?

Answer 1

The solution can be found out by applying Bernoullis theorem. The height of chocolate in the tank is not given. Therefore the solutions are in terms of H.