PART 1: ENERGY IN THE HOME, PERSONAL ENERGY USE AND HOME ENERGY EFFICIENCY.
Calculate your personal Annual Energy Usage for the following – list all data in kWh (KiloWatt hours):
• Space Heating (Central heating, room heaters etc. – if you share the central system, like in a flat or Hall, claculate your personal use).
• Space cooling (if you have air conditioning at home)
• Cooking (Gas cooker, microwave, sandwich toaster etc.)
• Lighting (All lights in your house/flat)
• Other domestic use (TV, Electronics, including computers, X-box etc)
• Transport (Public transport/car/motor cycle, including air travel if used)
Total ______________kWh
Convert this figure to kg of CO2 (Carbon dioxide) and Tonnes of Oil Equivalent (TOE). State clearly the basis for your calculations.
If you use the web based calculator you must check that conversions are appropriate for your location.
(If calculator does not state conversion factors, you could usually determine them by putting single inputs (e.g. 1000kW electricity) into calculator and seeing what the output is).
• TOTAL (kg of CO2)…………………
• TOTAL (TOE)……………………….
• The average UK per capita consumption is ~4TOE/annum,
• The average UAE per capita consumption is ~11TOE/annum
• Suggest why your figure might differ significantly from this.
NOW:
a) Identify one item of the energy saving equipment which you can incorporate in your house/flat/room or apartment block to replace one of your existing items mentioned above.
(Address a more sophisticated energy saving measure than low energy light bulbs)
b) Calculate the installed cost of item and the annual savings (energy and financial) which would result.
c) Hence estimate the simple payback period.
d) Why have you not installed this equipment? (Note: if you live on Campus or rent a room, imagine you are the owner the flat apartment block etc. when answering this question).
PART 2 EFFICIENT USES OF ‘WASTE’ HEAT AND RENEWABLE HEAT SOURCES
1) Describe how you might recover heat from (a) the process exhaust gas stream (e.g. from an oven) and (b) the process warm water stream (e.g. from a commercial dishwasher). Discuss any aspects of streams which may influence your choice of heat recovery system.
2) Industrial dryer operates for 60 hours/week, 50 weeks/year. It exhausts 200 kW/hr of heat and value of the energy is 6p/kWh. Heat exchanger of 50% efficiency is put into exhaust stream to recover the proportion of this heat. Installed cost of the heat exchanger is £22,500. The heat exchanger pressure drop needs a 2 kW fan to overcome it, and the cost of electricity is 10p/kWh. Calculate simple payback period for installation, taking into account the running costs, as well as benefits.
3) Domestic air conditioning unit has the COPc of 2 Thinking of the refrigeration cycle and the inefficiencies in various components, how could you attempt to increase the COP by modifying components?
4) Industrial dryer in Question 2 currently uses the heat exchanger for heat recovery. If exhaust air is highly humid, as would be common on a dryer, there would be advantages in recovering latent heat as well as sensible heat. (Often you will find that the latent heat content is substantially greater than the sensible heat content).
Examine how you may configure the heat pump that can recover the latent heat (and sensible heat) from the exhaust air then deliver it to incoming fresh air. Is it possible now to recycle the exhaust air? If so, how would you reheat it?
5) Prime movers are being studied for powering combined heat & power (CHP) units in the home and in industry.
Sketch how heat from these prime movers (like a gas turbine, a small Diesel engine or another prime mover) can be recovered for (a) water heating, (b) providing chilled water (an outline of the appropriate refrigerating equipment is required).