Are portable clothes dryers the very solution to space-scarce households in drying clothes indoors in the coming rainy, humid weather?
The Consumer Council has put to test a total of 5 models: 4 of these innovative clothes dryers work by generating warm air, with a fan heater, inside a balloon-like cover to dry the clothes, while one other model is similar to a garment bag but embedded with heating wire.
All models are portable in that they can be assembled with relative ease and put away in storage when not in use.
They may seem like a good alternative to the conventional tumble dryers. But the test results showed quite otherwise in terms of performance - drying speed and energy efficiency.
The performance tests were carried out in simulation to actual household application using cotton towels, T-shirts and jeans, taking reference from the IEC (International Electrotechnical Commission) standard stipulated for tumble dryers.
In the test, the same type and quantity of wet clothes were put to dry for the whole duration of the full-cycle operation of the 4 models of clothes dryers - 3 hours in 3 models and 6 hours in 1 model. The results turned out to be rather disappointing.
None could fully dry the clothes after one cycle; the content of moisture after the test was measured to range from 20% to 41% - the better score was achieved by the model with an operation cycle of 6 hours, doubling the drying time of the other 3 models.
The results clearly showed that the drying speed of these devices left much to be desired. Despite the long drying time taken, they could only partially dry the clothes. The actual drying time is largely depending on the quantity and material of clothes to be dried.
The drying bag model fared even more unsatisfactorily - the moisture content stood at 46%, barely half dry after 3 hours.
On energy efficiency, the 4 models were tested and measured to range from 0.81 to 1.14 kWh per kg of clothes, which on the basis of $1.1 per kWh the electricity cost (for drying a load of wet clothes which weigh 5.6 kg when dry) would run from $5 to $7. This compares unfavourably with the energy consumption of an average electric tumble dryer of 0.81 kWh per kg of clothes.
The energy efficiency of the drying bag was even lower - at 2.5 kWh per kg of clothes.
Nevertheless, these samples are generally considered to be more gentle in treating clothes than tumble dryers.
In addition to performance, the samples were tested for safety - on protection against water ingress, construction, insulation and material resilience against heat and fire.
The plastic materials of all samples were judged inadequate in resilience against heat and fire posing potential risk of fire accident. One sample made with insulation sheets for wiring was found to be insufficient in thickness and in the number of layers for protection to the users.
Another sample was found without the provision of drain holes to avoid accumulation of any dripping water inside the fan heater which could potentially result in short circuit.
Furthermore, users are reminded to always fit in the heater cover during installation every time, which expels any dripping water from getting into the fan heater.
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- 2014.03.17