Question

1. Compare heat transfer modes in the heaters below. For simplicity, the heaters are located in a room with () walls, (ii air, and (ii) a person in it. Explain how heat is transferred by conduction, convection, and radiation in type (a) and (b) to (), (ii, and (ii. Also, discuss in which type, the air become more dryer than the other, why? (30 pt) (a) (b) 바람이 솔솔-추운 창문 앞 설치 노출형 난방기 설치모습 아기목욕을 위해 욕실에 설치 My iend 고급빌라 거실에 설치 현관문 위 천정에 설치 욕실 샤워부스 위 설치

Answer 1

First of all, if we could try and understand the difference between both the heaters the solutions become much easier. In the given question, the heaters are completely different and the mode of heat transfer, eventually, is completely disparate as far as heat transfer goes.

In (a) it is an infrared heater which uses radiation to transfer. In this case, heating a room with four walls becomes more efficient than the other two cases simply because this kind of heater is basically used for localized spaces and it makes heat transfer more efficient in such cases. The heat transfer is mainly by radiation from the heater to the surroundings and depending on the medium, if there are walls there might be conduction between the walls and if there is air there is convection along with the radiation from the heater.

In (b) it is a portable heater, often used in homes. In this case, the mode of heat transfer is primarily convection and heating a room in the air is usually of greater effect given the mode of heat transfer. In a concise space using such heaters become a disadvantage as the air is locked inside and recirculated, causing skin related problems.

As mentioned earlier in (i), (ii), (iii), based on the modes of heat transfer the explanation can be summarized.

In comparison to both the heaters, portable heaters (b) turn the air dryer by removing moisture from the surroundings and recirculating the warm air. In infrared heaters, the process is purely radiation and direct heating and in a way more efficient and safer.