PE Mechanical HVAC case studies
PE Mechanical HVAC · Put your knowledge to work in context.
The Principles and Practice of Engineering (PE) exam in Mechanical: HVAC and Refrigeration is one of more than 20 PE exams administered by NCEES, the body that writes and delivers the exams used by U.S. state licensing boards. NCEES describes the PE exam as testing "for a minimum level of competency in a particular engineering discipline," and it is designed for engineers who have gained a minimum of four years of post-college work experience in their chosen discipline. The HVAC and Refrigeration discipline is aimed at engineers who design, specify, commission, and troubleshoot building environmental control and refrigeration equipment rather than machine components or utility thermal systems. The PE Mechanical HVAC case studies are 5 cases and about 2,187 words.
1Cooling-Coil Bypass and Latent Capacity at Two Apparatus Dew Points
A 10,000 cfm built-up AHU at sea level takes mixed air at 80°F dry-bulb and 67°F wet-bulb. The chilled-water coil has a manufacturer's bypass factor of 0.15 and an apparatus dew point of 50°F.
508 words, about 3 min2VAV Minimum Airflow, Reheat, and Ventilation in an Interior Zone
A 20,000-cfm VAV air handler serves an interior office zone with a design cooling load of 4.5 tons and design airflow of 2,000 cfm. At a low-occupancy winter condition the zone load falls to 0.5 ton, but the VAV box minimum is set at 40% (800 cfm).
472 words, about 2 min3R-410A Rooftop Unit: Undercharge Versus Liquid-Line Restriction
A 25-ton R-410A packaged rooftop unit serving a retail space is reported as not keeping up on a 95°F day. Measured values are: suction pressure 100 psig, suction-line temperature 50°F, discharge pressure 350 psig, liquid-line temperature 105°F.
383 words, about 2 min4Condensation on a Chilled-Water Pipe: More Insulation or Better Vapor Barrier?
A 4-in nominal chilled-water pipe (4.5-in OD) carries 40°F water through a 95°F, 85% RH mechanical room. It is insulated with 1 in of fiberglass (k = 0.25 Btu·in/h·ft²·°F) with an aluminum jacket.
407 words, about 2 min5Condenser-Water Pump Cavitation After Strainer Fouling
A 1,200-gpm condenser-water pump takes suction from a cooling-tower basin. The pump centerline is 4 ft above the basin water level.
417 words, about 2 min