Use LEFT and RIGHT arrow keys to navigate between flashcards;
Use UP and DOWN arrow keys to flip the card;
H to show hint;
A reads text to speech;
28 Cards in this Set
- Front
- Back
|
Using the psychrometric chart, find the enthalpy if the dry-bulb temperature is 20 0C and the wet-bulb temperature is 15 0C.A) 40 kJ/kgB) 45 kJ/kgC) 55 kJ/kgD) 50.5 kJ/kgE) 42 kJ/kg |
E |
|
|
Changes in moisture content of the air can be accomplished by the addition or removal of __________ to or from the air.A) sensible heatB) latent heatC) evaporative heatD) superheated heatE) temperature |
B |
|
|
During sensible heating:A) the relative humidity remains unchangedB) the relative humidity increasesC) the dewpoint temperature increasesD) the specific volume decreasesE) the relative humidity decreases |
E |
|
|
An average effective temperature chart can be applicable under the following conditions except when:A) customary indoor clothing is wornB) the heating method is warm airC) activity is high or heavy muscular work is being doneD) the heating method is steamE) the heating method is hot water |
C |
|
|
Effective temperature is defined as a measure of comfort which involves:A) the effects of relative humidityB) the effects of air movementC) the effects of dry-bulb temperatureD) the effects of wet-bulb temperatureE) all of the above |
E |
|
|
If 6.52 m3/s of air enters a cooling coil @ 30 0C dry-bulb and 17 0C wet-bulb. Leaves the cooling coil @ 200C dry bulb. What is the change in enthalpy? Answer = kJ/kg |
10.4 |
|
|
During sensible cooling:A) relative humidity decreasesB) enthalpy increasesC) wet-bulb temperature increasesD) relative humidity increasesE) dewpoint temperature increases |
D |
|
|
Which of the following statements about cooling and dehumidification is false?A) Air washers are used to dehumidify air.B) When air leaves the washer it will be close to 100% relative humidity.C) The spray water carries off the latent heat of condensation of the water vapour in the air.D) Dry bulb temperatures are increased.E) Dewpoint temperatures are lowered. |
D |
|
|
A humidifier is used in a ventilation system which handles 5.35 m3/s of air entering @ 30 0C dry-bulb, and 13.5 0C wet-bulb. The desired leaving air conditions are 30 0C, and 50% relative humidity. A) what is the mass of air flowing? Answer = kg/s B) What s the volume of air leaving the humidifier? Answer = m3/s C) What is the amount of moisture added? Answer = kg/s |
6.21 5.45 .064 |
|
|
Identify, from the list below, the combined psychrometric processes 1 heating and cooling2 cooling and humidification3 cooling and dehumidification4 mixtures of airA) 1, 2B) 2, 3C) 3, 4D) 1, 2, 3E) 1, 2, 3, 4 |
E |
|
|
Using the psychrometric chart, find the specific volume, if the dry-bulb temperature is 250C and the wet-bulb temperature is 20 0C.A) 0.84 m3 / kgB) 0.852 kg / mC) 0.85 m3 / kgD) 0.90 m3 / kgE) 0.862 m3 / kg |
E |
|
|
Air used for ventilating purposes in an office building should be kept within certain range of relative humidity as indicated below. ( REFER TO COMFORT CHART )A) 30 to 50 %B) 30 to 70 %C) 40 to 50 %D) 50 to 60 %E) 10 to 30 % |
B |
|
|
Using the psychrometric chart, find the specific volume if the dry-bulb temperature is 28 0C, and the wet-bulb temperature is 21 0C. Answer = m3/kg |
0.87 |
|
|
Using the psychrometric chart, find the moisture content if the dry-bulb temperature is 34 0C, and the wet-bulb temperature is 28 0C. Answer = kg of water vapour / kg of dry air |
0.0216 |
|
|
Using the psychrometric chart, find the relative humidity if the dry-bulb temperature is 250C and the wet-bulb temperature is 25 0C.A) 50%B) 90%C) 100%D) 95%E) 60% |
C |
|
|
If 6.52 m3/s of air enters a cooling coil @ 30 0C dry-bulb and 17 0C wet-bulb. Leaves the cooling coil @ 200C dry bulb. What is the volume of air leaving the coil? Answer = m3/s |
6.3 |
|
|
If 3.75 m3/s of air enters a heating coil @ 23 0C dry-bulb and 12 0C wet-bulb. Leaves the heating coil @ 320C dry bulb. What is the volume of air flowing out of the heating coil? Answer = m3/s |
3.85 |
|
|
Using the psychrometric chart, find the moisture content if the dry-bulb temperature is 18 0C, and the wet-bulb temperature is 11 0C. Answer = kg of water vapour / kg of dry air |
0.0053 |
|
|
Using the psychrometric chart, find the relative humidity if the dry-bulb temperature is 250C and the wet-bulb temperature is 20 0C.A) 64%B) 70%C) 52%D) 72%E) 75% |
A |
|
|
If 5.0 cubic metres per second of air enters a heating coil at 20 0C dry-bulb and 15 0C wet-bulb, and leaves the heating coil at 30 0C dry-bulb, what is the change in enthalpy?A) 52 kJ/kgB) 42 kJ/kgC) 15 kJ/kgD) 20 kJ/kgE) 10 kJ/kg |
E |
|
|
A dehumidifier is used in a ventilation system which handles 3.87 m3/s of air entering @ 25 0Cdry-bulb, and 24 0C wet-bulb. The desired leaving air conditions are 25 0C, and 30% relative humidity. A) what is the mass of air flowing? Answer = kg/s B) What is the volume of air leaving the dehumidifier? Answer = m3/s C) What is the amount of moisture removed? Answer = kg/s |
4.45 3.79 .0534 |
|
|
If 6.52 m3/s of air enters a heating coil @ 30 0C dry-bulb and 17 0C wet-bulb. Leaves the cooling coil @ 200C dry bulb. What is the mass of air leaving the coil? Answer = kg/s |
7.52 |
|
|
During sensible heating which of the following results is true?A) dry-bulb temperature lowersB) wet-bulb temperature remains constantC) relative humidity increasesD) enthalpy remains constantE) none of the above |
E |
|
|
A humidifier is used in a ventilation system which handles 4.17 m3/s of air entering @ 22 0C dry-bulb, and 10 0C wet-bulb. The desired leaving air conditions are 22 0C, and 30% relative humidity. A) what is the mass of air flowing? Answer = kg/s B) What is the volume of air leaving the humidifier? Answer = m3/s C) What is the amount of moisture added? Answer = kg/s |
4.97 4.18 0.0109 |
|
|
If 5.0 cubic metres/second of air enters a heating coil at 20 0C dry-bulb and 15 0C wet-bulb, and leaves the heating coil at 30 0C dry-bulb, what is the mass of air flowing?A) 5.94 kg/secB) 6.84 kg/secC) 5.0 kg/secD) 6.2 kg/secE) 5.4 kg/sec |
A |
|
|
If 3.75 m3/s of air enters a heating coil @ 23 0C dry-bulb and 12 0C wet-bulb. Leaves the heating coil @ 320C dry bulb. What is the heating capacity of the coil? Answer kJ/s or kW |
40.7 |
|
|
Using the psychrometric chart, find the dewpoint temperature if the dry-bulb temperature is 25 0C and the wet-bulb temperature is 20 0C.A) 17.5 0CB) 14 0CC) 20 0CD) 16 0CE) 19 0C |
A |
|
|
An increased air flow increases heat loss of the body bywhich of the following methods: 1) convection 2) conduction 3) evaporationA) 1 onlyB) 2 onlyC) 1 and 3D) 1 and 2E) 1, 2, and 3 |
E |
