Solar thermal collectors and applications
WATSUN simulation program
WATSUN simulates active solar systems and is developed by the Watsun Simulation Laboratory of the University of Waterloo in Canada [119]. It is a ready-made program that the user can learn and operate easily. It combines collection, storage, and load information provided by the user with hourly weather data for a specific location, and calculates the system state every hour. For convenience, a monthly summary is also provided. Both hourly and monthly reports include data about incident solar radiation, energy collected, load and auxiliary energy. WATSUN provides information necessary for long-term performance calculations. Also included with WATSUN is an economic analysis option, that can be used to assess the costs and profits generated by the use of the solar energy systems.
WATSUN uses weather data consisting of hourly values for global radiation on a horizontal surface, dry bulb temperature, wind speed and relative humidity. For those locations where hourly data is not available, synthetic hourly data can be generated using WATGEN synthetic weather generator, which needs only monthly average values as input.
The WATSUN simulation interacts with the outside world through a series of files. A file is a collection of information, labelled and placed in a specific location. Files are used by the program to input and output information. There is one input file defined by the user, called the simulation data file. The simulation program then produces three output files, a listing file, an hourly data file, and a monthly data file.
The system is an assembly of collection devices, storage devices, and load devices that the user wants to assess. The system is defined in the simulation data file. The file is made up of data blocks that contain groups of related parameters.
The simulation data file controls the simulation. The parameters in this file specify the simulation period, weather data and output options. There are many systems that can be modelled, including domestic hot water, pool systems, and industrial process heating systems. Different data must be entered for each type of system.
The simulation data file also contains information about the physical characteristics of the collector devise, the storage device(s), the heat exchangers, and the load. When the simulation data file has been fully delineated, the simulation requires one more file, the weather file, before it can run.
