Q 1: What is the energy density of petrol?
Explanation: Energy density is the amount of energy that can be stored in a given system, substance, or region of space. It can be expressed as energy per volume or energy per mass. The energy density of wood is 10 to 16 MJ/kg. The energy density of coal is 24 MJ/kg. The energy density of petrol is 46 MJ/kg. The energy density of natural gas is 55 MJ/kg. The energy density of hydrogen is 120 to 150 MJ/kg.
Q 2: Renewable energy is known as “green energy” because:
Explanation: Green energy is referred to as clean, sustainable, or renewable energy. So, it does not release toxic gases.
Q 3: What is the energy density of Hydrogen:
Explanation: The energy density of hydrogen: 120 to 150 MJ/kg.
Q 4: The diffuse radiation:
Explanation: Diffuse radiation follows a scattered and uncertain path.
Q 5: What is the standard value of the solar constant?
Explanation: The standard value of the solar constant is 1.366\;kW/m^2 .
Q 6: A solar thermal collector:
Explanation: A solar thermal collector collects and converts the solar energy into thermal energy and delivers it to heat transfer fluid.
Q 7: The concentration type of solar collectors:
Explanation: The primary purpose of concentrating solar collectors is to concentrate solar energy from the Sun.
Q 8: The value of concentration ratio of flat plate collector is:
Explanation: Concentration ratio (CR) is defined as the ratio of the area of the aperture of the collector system to the area of the receiver. For flat plate CR = 1; For line focus CR = 100; For point focus CR = 1000.
Q 9: In evacuated tube collectors:
Explanation: The air between the two glass tubes is removed to form a vacuum, which reduces conductive and convective heat loss.
Q 10: When did the oil crisis happen?
Explanation: During the Gulf war, prices of oil got increased due to the 1973 oil crisis. The International Energy Agency (IEA) was established in 1974 in the wake of oil.