Answer the following statement(s) true (T) or false (F)
1. Relay contacts are designated as normally open, or normally closed. In this context, the word “normally” means when the coil of the relay is not energized.
2. There are hydronic heating applications where control action is required based on the difference between two temperatures rather than the value of either temperature.
3. A multizone relay center is designed to isolate the wiring and control operation of several independent zone circulators or zone valves.
4. One purpose of mixing is to protect conventional boilers from operating at conditions that allow sustained flue gas condensation.
5. Direct injection mixing, whether accomplished using a two-way valve or variable-speed pump as the injection control device, provides the highest temperature difference between the supply and return injection risers.
1. True
2. True
3. False
4. True
5. True
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When the sampling frequency fs = 20 kHz, the time required for a 10-bit staircase quantizer to make a comparison is T?=_____(x.xxx) ?s.
Fill in the blank(s) with the appropriate word(s).
Answer the following statement(s) true (T) or false (F)
1. Mobile engine designs typically aim for several thousand hours of life. 2. Fuel cells are said to be high emission technologies. 3. Any engine meant to drive a moving platform has to be compact but still robust 4. Methanol is very corrosive and has an affinity for water that makes transporting it difficult. 5. Fuel cells directly drive power shafts, whereas ICE engine sets generate electric currents.
It is believed that sweet acidophilus milk is more easily digested than standard milk
Indicate whether the statement is true or false
A system comprised of chloroform, 1,4-dioxane, and ethanol exists as a two-phase vapor/liquid system at 50°C and 55 kPa. After the addition of some pure ethanol, the system can be returned to two-phase equilibrium at the initial T and P. In what respect has the system changed, and in what respect has it not changed?
(a) How many phase-rule variables in addition to T and P must be chosen so as to fix the compositions of both phases? (b) If the temperature and pressure are to remain the same, can the overall composition of the system be changed (by adding or removing material) without affecting the compositions of the liquid and vapor phases?