Albuquerque, New Mexico
June 24, 2001
June 24, 2001
June 27, 2001
6.89.1 - 6.89.4
A Psychrometric Test Facility for the Undergraduate Laboratory William S. Johnson The University of Tennessee
This paper describes a laboratory test facility designed, built and tested by undergraduate students. The facility incorporates industrial hardware including electric heating coils, a cooling coil with a chiller, a rotary enthalpy recovery heat exchanger, a humidifier, a blower and three remotely controlled dampers along with instrumentation to measure airflow, various temperatures and relative humidities throughout the system. An instrumentation and control system has been integrated into the facility.
Under the ASHRAE (American Society of Heating, Refrigeration and Air Conditioning Engineers) Undergraduate Senior Project Grant Program, undergraduate students at the University of Tennessee designed and constructed a comprehensive laboratory setup for use in psychrometric studies. The local ASHRAE chapter assisted in procuring equipment. Students enrolled in a special topics class completed the design work and performed much of the actual construction over a two-year period. The first year, students designed and built a duct system incorporating a cooling coil, a two-stage heater, a variable speed fan, a humidifier and needed flow, temperature and humidity instrumentation. The second year, students modified the system for the additional testing of a rotary enthalpy recovery unit. Both groups calibrated the systems, wrote operational procedures and designed experiments for the departmental undergraduate laboratory.
The system is shown schematically in Figure 1. Room (or outside) air enters the rotary heat exchanger at flows up to 600 CFM (.283 m3 / s) then passes through the variable speed fan, a one-ton capacity cooling coil, a two-stage 4-kW heating coil and a steam humidifier before exiting through the other side of the rotary heat exchanger. The air can be cooled to around 33 o F (0.5 oC) or heated to about 140 oF (60 oC) with relative humidities between about 15% and 95% before exhausting through the heat exchanger.
Instrumentation included six RTD type temperature transducers, five humidistats for relative humidity measurement and two pitot-type volumetric flow meters. Locations of each are shown in Figure 1. The instrumentation and control system is a SIEBE environmental system, which allows on-screen monitoring of all variables, on screen damper control and controlling certain variables to preset values.
“Proceedings of the 2001 American Society for Engineering Education Annual Conference & Exposition Copyright 2001, American Society for Engineering Education”
Johnson, W. (2001, June), A Psychrometric Test Facility For The Undergraduate Laboratory Paper presented at 2001 Annual Conference, Albuquerque, New Mexico. https://peer.asee.org/9705
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