DWSIM is an open-source chemical process simulator. For educational purpose, its capabilities are comparable to commercial simulators such as Aspen Plus, Aspen HYSYS, ChemCAD, ProSim, etc. The objective of this paper is to present a model of NH3-H2O vapor absorption refrigeration system in DWSIM. Simulation results of this model are compared with those of Aspen HYSYS. NH3-H2O vapor absorption refrigeration system consists of absorber, evaporator, pump, generator, rectifier, condenser, evaporator, and valves. It provides examples of common chemical engineering processes such as heat transfer, mass transfer, condensation, evaporation, throttling, gas-vapor separation, absorption, and desorption. Sensitivity and optimization analyses can be performed using the DWSIM model presented in this paper. Therefore, it is expected that this model will not only teach a student about chemical engineering in general and vapor absorption refrigeration in particular, but also enhance the student's skill in using DWSIM.