HOT WATER CIRCUIT
HOT WATER CIRCUIT PRODUCTS 55 into the machine, and needs to be heated up
again.
However, there is potential benefit for customers who have hot water supplied from renewable energy resources which allows hot water supply at a much lower cost [6]. Thus, there is an ongoing debate on using cold water filled washing machine or hot and cold water filled washing machines in the market.
Working Mechanism
Performance
HWC products manage to achieve an accomplishment of hunting two birds with one stone. On one hand, it saves electricity from the heating process water in the machine which is the main part of electricity consumption.
Instead, the process water in the machine is heated up by hot water that runs into the machine via a heat exchanger. On the other hand, it enables a system technical advantage by creating a closed hot water loop which keeps temperature constant. It solves the typical problem of hot water fill machine that hot water supply from domestic boiler is energy-intensive. As mentioned before, hot water from a domestic boiler becomes cold when it reaches machine and needs to be heated up again which is inefficient [1].
Principle
HWC products could be connected to the hot water circuit from renewable energy heat supply, such as district heating, solar energy and geothermal energy. New components of heat exchangers, new connections, heating
water valve, and updated software are added to HWC products and the electricity heating-up system is still retained as backup system [7].
One of the two new connections adds flows of hot water from the hot water supply circuit and the other one leads the water back to the heating plant after the heat exchange. These two new connections substitute the conventional electricity heater.
For dryers, especially, larger condenser and circulation fan engines are needed to ensure working efficacy.
Hot water flowing into the machine to heat up the process water has a minimum temperature requirement of 55°C. Normally, heating hot water should be 10°C higher than process water requirement. For example, if the process water needs to be at a temperature of 60°C,
HWC dryer (above) and HWC washing machine below [7]
Orange: heat exchanger Red: hot water included Blue: outgoing hot water
Magnification: Heatwater (red) heats the process water (yellow to orange)
then hot water supply at the temperature of 70°C is required in order to meet the heat demand. HWC washing machine and dish washer have high performance at the temperature of 60°C.
Back-Up System
As the heat exchange happening between hot water and process water, the temperature difference will decrease and the heat exchange efficiency goes down. When higher temperature is required, the electricity system will be switched on automatically to heat up the process water [4]. It could of course also be used in the situation when there is no hot water supply.
Demonstration Projects
Several demonstration projects were implemented in different areas, such as Gothenburg and Västerås, to prove that more could be done to make use of district heating to replace electricity by ensuring energy efficiency and increasing household comfortability. These projects are regarded with high environmental value, because environmental impact is significantly reduced, given the fact that electricity results in large CO2 emissions [4]. HWC products are equipped in the building connected to a new circuit from a district heating plant in about 200 households with new, non-conventional installations [8]. Sparse heat houses built in Gothenburg in 2006 equipped with HWC products strikes a successful case by demonstrating that HWC products achieved 697 kWh electricity consumption reduction annually. It represents 80-90% of the electrical energy consumption for household appliances [1]. In other words, HWC products could help households save up to 90% of this consumption per year.
Barriers
Even though there are successful cases to demonstrate HWC product efficiency and environmental efficacy, there are several challenges for HWC products to overcome for its commercialisation at large scale based on current market analysis.
Cost of installation
HWC products can only be installed primarily with new construction of a building with new circuit built connected to district heating plant or other renewable energy heat supply. It would be expensive to install HWC products afterwards into single households [9].
Public acceptance
As mentioned in the market analysis sector, hot water-filled washing machines have been on the market for decades but their sales gradually decreased.
The manufacturers are now more focusing on only cold water filled washing machine production with the innovation of detergent technology. More attention is shifting to increase cleaning efficiency of detergents that could be used in cold water. For instance, biological detergents could only be used in water at temperatures below 40°C, otherwise the enzymes contained in the detergent would die off [5]. Thus it makes the hot water filled function unnecessary and connected to additional cost.
In addition, there is an argument that hot water decreases washing efficiency by increasing washing time, and it adds extra wear and tear to the washing machine.
Large-scale commercialisation Besides ASKO company which is the research leader on HWC products involved in the Remote Viewing Project, no other household appliance manufacturer seems interested in this
HOT WATER CIRCUIT PRODUCTS 57 topic so far. There lies a challenging question
how to convince the home appliance industry to make products with consideration of the interest of district heating and thus increase HWC product production and broaden its market?
References
[1] Swedish District Heating Association, District heating-powered appliances and white goods with hot water connection. Retrieved December 11, 2011, from
http://www.svenskfjarrvarme.se/Medlem/Fokuso
mraden-/Fjarrvarldens-omvarld/Energieffektivistering/Energieffektiviseri ngsexempel/Bostader/vitvaror/.
[2] Ingulf, Olof, Smith, Roger, & Göteborg Energi AB. (2006). Demonstration projects heating adapted house Gothenburg, Advanced district heating use in houses.
Swedish District Heating Ltd.
[3] ASKO, HWC Products Guide. Retrieved December 11, 2011, from
http://www.asko.se/hwc/hwc-interaktiv-guide/.
[4] Hof, Hans, J. (1996). The district Heating Kitchen.
Assoc. of Energy Distribution Companies in the Netherlands, EnergieNed.
[5] Run Washing Machines with Solar Hot Water.
Retrieved December 11, 2011, from
http://www.reuk.co.uk/Run-Washing-Machines-with-Solar-Hot-Water.htm.
[6] Should I buy a cold fill washing machine or hot and cold fill? Retrieved December 11, 2011, from
http://www.washerhelp.co.uk/buying-related_2.html.
[7] ASKO. How does HWC work. Retrieved December 11, 2011, from
http://www.asko.se/hwc/hwc-produkter/.
[8] Swedish District Heating Association , Heat Sparse House Retrieved December 11, 2011, from http://www.svenskfjarrvarme.se/Medlem/Fokuso
mraden-/Fjarrvarldens-omvarld/Energieffektivistering/Energieffektiviseri ngsexempel/Bostader/Varmeglsea-smahus/.
[9] Martin Bang-Hansen. (2011). Interview with ASKO Company Marketing Manager. December 6, 2011.
Pictures of ASKO products reprinted with permission from the company.