1. History and Market Trends of Dishwashers
– The first mechanical dishwasher was patented in 1850 by Joel Houghton; it was made of wood and hand-cranked.
– In 1865, L.A. Alexander patented a hand-cranked rack system, but neither design was widely accepted.
– Josephine Cochrane invented a successful hand-powered dishwasher in 1886, unveiled at the 1893 World’s Fair.
– Europe’s first electric dishwasher was created by Miele in 1929, while the UK’s William Howard Livens invented a non-electric model in 1924.
– By the 1970s, dishwashers became common in North America and Western Europe, with over 75% of homes in the US and Germany having dishwashers by 2012.
– The postwar boom in the 1950s led to increased adoption of dishwashers among wealthy households.
– Standardized sizes and designs facilitated integration into modern kitchens.
– Growth in energy conservation features responded to consumer demand for efficiency.
– There has been a shift in perception regarding dishwashing, recognizing convenience and time-saving benefits.
2. Design Features and Types of Dishwashers
– Standard dimensions are 60cm width (Europe) or 24in (US), with a minimum height of 86cm (Europe) or 34in (US).
– Portable dishwashers are available in 45 and 60cm widths, featuring casters and countertops.
– Domestic dishwashers are designed for home use, while industrial models are available for commercial establishments.
– Integrated models fit under kitchen countertops, and energy-efficient models were introduced in the late 1990s.
– Dish drawer models introduced by Fisher & Paykel in 1997 allow independent operation of drawers.
– Commercial dishwashers operate at higher temperatures (65-71°C / 149-160°F) for sanitation and often utilize chemical sanitizers or booster heaters for final rinse temperatures of 82°C (180°F).
3. Cleaning Mechanism and Technology
– Dishwashers utilize hot water spray (45-75°C / 110-170°F) for cleaning; delicate items require lower temperatures.
– A mixture of water and detergent is pumped to rotating sprayers, with recirculation conserving water and energy.
– The cleaning cycle includes pre-rinse, main wash, rinse cycles, and drying methods.
– Soil sensors measure food particles and adjust washing time based on cleanliness detected.
– Mid-range dishwashers often include hard food disposal units, and microprocessor-controlled wash cycles adjust duration based on dirt levels.
– Energy Star certification criteria require ≤ 270 kWh/year for standard dishwashers, and most operate at 75°C (167°F) for sanitizing.
4. Environmental Impact and Detergent Regulations
– Dishwashers generally use less water and energy compared to hand washing; a peer-reviewed study indicates hand washing can use 20-300 liters of water versus 15-22 liters for dishwashers.
– Energy-efficient dishwashers consume 1 to 2 kWh compared to 0.1 to 8 kWh for hand washing.
– Phosphates have been banned in many regions due to environmental concerns, particularly eutrophication; 17 US states have partial or full phosphate bans in dish detergents.
– The EU Directive 76/769/EEC bans nonylphenol and nonylphenol ethoxylates in rinse aids.
5. Vulnerabilities of Materials and Alternative Uses
– Glassware issues include white haze from mineral deposition, irreversible cloudy appearance due to alkaline detergents, and potential health risks from lead in lead crystal.
– Strong detergents and high temperatures can discolor aluminum, brass, and copper, while nonstick coatings deteriorate, and fragile items risk damage from collisions.
– High temperatures can harm many plastics, especially near heating elements; carbon steel tools can corrode in extended moisture.
– Dishwashers can also be used for alternative purposes, such as cooking foods at low temperatures, cleaning various household items, and even controversial uses like cleaning vegetables, though not recommended for greasy tools. https://en.wikipedia.org/wiki/Dishwasher
