Q1: Which of the following parameters is not responsible for the heat loss from a hot steam carrying bare pipe surface located in a room without fans ?

ANS:D - none of these.

The correct answer, "none of these," indicates that all of the parameters listed—emissivity of the pipe surface, diameter and length of the pipe, and temperature of the hot pipe surface and that of the air in the room—are responsible for heat loss from a hot steam carrying bare pipe surface located in a room without fans. Here's a brief explanation:

1. Emissivity of pipe surface: Emissivity refers to the ability of a surface to emit thermal radiation. A higher emissivity means that the surface emits more radiation and thus contributes to heat loss. Therefore, the emissivity of the pipe surface directly affects the rate of heat loss.
2. Diameter and length of the pipe: While the diameter and length of the pipe may not directly affect the rate of heat loss per unit area, they do influence the total surface area exposed to the surrounding air. A larger surface area results in more heat transfer to the surrounding air and thus contributes to overall heat loss.
3. Temperature of hot pipe surface and that of the air in the room: The temperature difference between the hot pipe surface and the air in the room is a critical factor in determining the rate of heat transfer. A larger temperature difference results in higher heat transfer rates, leading to increased heat loss from the pipe surface to the surrounding air.

Therefore, all of the parameters listed—emissivity of the pipe surface, diameter and length of the pipe, and temperature of the hot pipe surface and that of the air in the room—play a role in determining the heat loss from a hot steam carrying bare pipe surface in a room without fans.