Posted: April 28th, 2016

Compute the efficiencies of electrical and space heating energy production, and the overall thermal efficiency. Create a graph with rate of gas energy input on the axis and electrical, heat and overall efficiencies in on a common y axis

. Convert the rate of gas consumption to a rate of gas energy consumption in kilowatts.
2. Compute the electrical output from the control panel and thermal output from the plant to the space heating system, given that the hot water flow rate is . Create a graph with rate of gas energy consumption on the axis and rates of both electrical and space heating energy delivery on a common axis
3 Compute the efficiencies of electrical and space heating energy production, and the overall thermal efficiency. Create a graph with rate of gas energy input on the axis and electrical, heat and overall efficiencies in on a common y axis
4 Normally, one defines “efficiency” as the ratio of the (rate of) useful energy output to the (rate of) (costly and/or environmentally damaging) energy input. However, this does not always fully represent the ratio of benefits to costs, because, for example, the same amount of energy input from different sources may have different environmental or financial costs (and, for that matter, the same amount of energy output in different forms may have different value).
Therefore, for the purposes of exercise 4, we will define an alternative measure of efficiency by the ratio of the usable portion of the total (electricity plus space heating) rate of energy output to the total rate at which carbon dioxide is emitted in supplying the input energy.
A CHP system is installed in the Davy building. The demand for space heating is enough to use only of the available space heating energy, but all of the electrical output can be utilised (either on-site, or by selling it on to the grid). Compare the efficiency (by the alternative definition given in the previous paragraph) of the plant with the efficiency, defined in the same, new way, that would be achieved by buying one’s electricity from the grid, and using a gas boiler for space heating. Assume that the plant has an overall maximum conversion of gas energy to space heating and electrical energies of , in the form of space heating and electricity.
You’ll need data on: