Heat Exchanger Analysis
Source: Alexander S Rattner and Christopher J Greer; Department of Mechanical and Nuclear Engineering, The Pennsylvania State University, University Park, PA
Heat exchangers transfer thermal energy between two fluid streams, and are ubiquitous in energy systems. Common applications include car radiators (heat transfer from hot engine coolant to surrounding air), refrigerator evaporators (air inside refrigerator compartment to evaporating refrigerant), and cooling towers in power plants (condensing steam to evaporating water and ambient air). The objective of this experiment is to introduce experimental measurement (rating) and modeling procedures for heat exchangers.
In this experiment, a water-to-water tube-in-tube heat exchanger will be constructed, and evaluated. Temperature and flow rate measurements will be employed to determine the heat transfer rate (Q) and overall conductance (UA). The measured heat exchanger UA will be compared with predicted values for the geometry and operating conditions.
1. Fabrication of heat exchanger system (see schematic and photograph, Fig. 2)
- Affix two plastic water reservoirs (~1 liter each) to a work surface (~0.6 m apart). If these are covered containers, drill holes in the lid for the inlet and outlet water lines and pump power cable. These will serve as the hot and cold water reservoirs.
- Mount one small submersible pump in each reservoir.
- Vertically mount two water flow meters (rotameters), one near each reservoir. Use soft PVC tubing to connect
Table 1 - Measurements and derived LMTD and UA values for heat exchanger at hot and cold flow rates of 0.20 and 0.15 l min-1.
