Building Services Engineering 5th Edition Handbook

166 Ventilation and air conditioning
25. How can an off-peak ice-making chiller be more efficient to operate than a daytime water
chiller?
1. Greater temperature difference between evaporation and condensing temperatures.
2. Lower outdoor night-time dry- and wet-bulb air temperatures.
3. Reduced electrical tariff.
4. Reduces peak hours electrical demand kW.
5. It is not more energy-efficient.
26. Which of these can affect asthma sufferers?
1. Excess of outside air ventilation.
2. House dust mites and mould spores.
3. Warm indoor air.
4. Humid and warm indoor air.
5. Matters other than those related to ventilation.
27. Which is the most efficient way of recovering energy from room air?
1. Recirculation.
2. Sensible heat recovery thermal wheel.
3. Total heat recovery thermal wheel.
4. Plate heat exchanger.
5. Run-around pipe coils.
28. How does a run-around pipe coil system function?
1. Closed pipe loop passes water by gravity circulation between heat source and sink
locations.
2. Outgoing air-duct water-cooled coil; closed cycle water pipework; warmed water
pumped through incoming outdoor air-duct coil, recovering useful heat.
3. Refrigerated evaporator coil in outgoing waste heat duct passes useful heat to
condenser coil in the incoming air duct.
4. Refrigeration system recovers waste heat in an outgoing air with a chilled-water coil in
exhaust air duct.
5. Cold-water feed pipe to domestic hot-water system preheated in an outdoor air coil in
warm weather.
29. What does a chilled beam mean?
1. Steel structural beam exposed in the occupied room and cooled by a supply air stream
from a directional grille.
2. Refrigerated pipe within a room.
3. Chilled-water pipes alongside structural floor beams.
4. Exposed steel beam at high level in a room having chilled-water pipes attached.
5. Natural convector chilled-water finned pipe.
30. Which water temperature flows through a chilled beam?
1. 6–12 ◦ C.
2. 4–18 ◦ C.
3. Below room air dew-point.
4. Minimum of room air temperature minus 10 ◦ C.
5. Above room air dew-point.