As the traditional way of thinking, CHP is unsuitable for space heating so we need to think outside the box to find the solution of this problem. Thus, we focused on hot water consumption that is lesser well known but significant and its account for 25% of domestic energy consumption in the UK and account for over 24 million tones of co2 emission annually. Hot water is not related to the weather so a solution can be repeated on a global scale. Thus, we need to prove that CHP is an option to cover hot water load or not?
Normally, British people consumed hot water around 40 liters/person/day which in our average household is 4 kWth/day and hot water usage in the UK is 67% for bath and shower and 20% is for the use in washing machines. However, there are different cases of hot water profile that can be analyzed such as different size of houses and the number of people living in houses.
This figure shows power load heating water on weekend and weekday for different cases. In case of four people living in the same size of house of two people has higher value than case of 2 people. The peak time period of weekend and weekday is quite different and it can be noticed that the trend of all of graph is similar to “M” curve that is in the typical hot water graph. REF: Domestic Hot Water Consumption in Four Low-income Apartment Buildings (E Vine etc al, 1987)
In this project there are 2 case studies that have different hot water profiles.
We using hot water tank to crush the problem with constant heat supply and variable heat demand and we also assumed to install economy-7 hot water tank to each flat in high rise.
The figure on the right hand side shows diagram of economy-7 hot water tank and inside each tank there are electrical immersion heating and a redundant heating coil design to be connected to a boiler.
This graph shows result of 2 case studies comparison and it can be concluded that the more efficiency CHP can match the hot water load better so it doesn’t produce as much waste heat. For the deficit of hot water requirement of high rise, it can meet with immersion heater in each hot water tank.
© University of Strathclyde 2009
