Which of the following statements are True Higher the HDD He

Which of the following statements are True? Higher the HDD (Heating Degree-Days) of a place, more severe is the winter. The sun is higher in the summer sky and lower in the winter, which is a key factor for passive solar design. All other things being equal, a building whose long side is south-facing would result in lower heating bills. Passive systems are generally installed for energy conservation after a house is fully constructed. A, B, C, B and C. Which of the following statements are true about a Fuel Cell? A fuel cell generates a direct flow of electrons instead of high temperatures. If the hydrogen fuel comes from the electrolysis of water driven by a renewable energy source, then using fuel cells eliminates greenhouse gases over the whole cycle. Fuel cell use an electrochemical process and functions like a continuous battery. A fuel cell is type of an internal combustion heat engine. A, B and C A, B, C and D. For power-generating machines such as a hydro turbine, water enter the rotor at_____________ periphery, and exit is at _________ periphery, so that energy can transferred from water to the rotor, but in case of power-consuming machines such as an air blower, fluid (air) enters at the _________ periphery and exits at ___________ periphery, so the energy is transferred from rotor to the working fluid. Inner, outer, Inner, outer outer, Inner, Inner, outer Inner, Inner, outer, outer outer, outer, Inner, Inner If 30,000 BTU/hr of heat is to be removed from a class room on a summer day, approximately size (rating) of air-conditioner unit would be ________ ton(s). Sketch a block-diagram of a refrigeration/have cycle showing and labeling key components & heat exchange processes.

Solution

(a) False

Heating degree Days can be defined as the number of days of a building of which heating should be provided on comparingit to the base temperature normally taken as 65F. The higher the no. of HDD the more no. of days the temperature falls below base temperature. HDD depends on the no of winter days but not the severity of winter.

(b) True

In a Passive Solar design the heating and cooling of a workspace or a building is done through solar enegry with the help of heat transfer through windows, conduction, convection and radiation, insulation, climatology and the position and direction of work space. The sun\'s position in summer and winter places a key role and by controling the apparture it can be optimised.

(C) True

South facing buildings will result in low heating bills because in winter it will keep down the heating costs simply by raising the curtains in froont rooms. In summer the sun angle will be high and south face buildings can get more light nd heat can be dispated for other use.

(d) False

It is better to prepare a pre-planning before construction as all passive systems can not be installed after construction.