﻿ During winter time you use an electric heater at 1000 W is under assume that heat transfer occurs
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### Question

During winter time, you use an electric heater at 1000 W is under assume that heat transfer occurs through Each of the four walls is composed of the layers shown in the following table: The indoor air convection coefficient is h1 = 5 W/m2. K and the outdoor air convection coefficient is ho = 10 w/m2. K. For an outdoor temperature of 5 degree C, calculate the indoor temperature when the electric heater is working continuously, If you use oil as energy source, determine the total mass of oil needed to heat the room for 12 hours, assuming that the heating value of the oil is 72000 kJ/kg. In order to minimize heat losses, some houses are built with a thicker layer of concrete. Calculate the savings in heat loss if the wall thickness is increased to 500mm with a new thermal resistance of 3. 68m2. K/W.

### Solution

xxy, xxx upper xxxx of xxx xxxxxxx xx not xxxxxxy visible. xxxx yxx xxxxxx a xxxxx and xxxxxxxxx xxx xxz, so xxxx i xxxxx xxxx yxx. thanks :)