Mandatory Report on chiller plant tour: due date May 23, 2019 (You can choose one topic)
Topic #1: Heat transfer analysis on the effect of mineral fouling (CaCO3) on the heat conduction in condenser tubes (typically 0.75” ID copper tube). Using heat conduction theory along the radial direction, estimate the performance loss in the heat transfer between cooling water flowing inside condenser tubes and refrigerant gas (e.g., R-11) outside tubes. Cooling water enters condenser tube (tubeside) at 75F and leaves at 85F, or higher, depending on the outside air temperature and humidity.
Mandatory Report on chiller plant tour: due date May 23, 2019 (You can choose one topic)
Topic #2: Refrigerant gas is superheated when it enters condenser shellside. The superheated refrigerant gas is cooled first to saturated gas and then eventually to saturated liquid refrigerant when it leaves the condenser (shellside). Thus, when the condenser tubes are clean, i.e., mineral fouling free, the temperature of the liquid refrigerant leaving condenser is almost equal to the water temperature leaving condenser. The difference between the two temperatures is called “condenser approach.” In other words, when a condenser is perfectly managed, the condenser approach is zero or one-two deg C. With severe mineral fouling inside condenser tube, the condenser approach temperature can be over 10 degC. Explain why the condenser approach temperature increases over 10 degC using mathematical equations from heat transfer and thermodynamic theories.
Mandatory Report on chiller plant tour: due date May 23, 2019 (You can choose one topic)
Topic #3: The maximum load of the chiller at Bossone building is 450 ton (refrigeration ton RT). When the chiller is running at the full capacity, the load is 100%, and the efficiency as measured in the unit of kW per RT is lowest (about 0.60 kW/ton). A refrigeration ton (RT) is equivalent to 12,000 BTU/h or 3.5 kW. When chiller operates at less than 100%, the efficiency is exponentially reduced. For example, at 50% load which is typical in cool summer days, the chiller efficiency drops (i.e., 0.85 kW/ton). Explain why the efficiency decreases when the load decreases using mathematical equations from heat transfer and thermodynamic theories.