Tumble Dryers: Chapter 1
Working of Tumble Dryers - I
By the end of this module, you should be able to describe:
The types of tumble dryers, and
The working of tumble dryers. Skip to quiz!
Types of Tumble Dryers
Before learning about the working of tumble dryers, we must go through the types of tumble dryers. We must classify the tumble dryers into two:
Vented Dryers, and
Ventless Dryers.
Vented tumble dryers are dryers with a vent. A vent removes the moist air from the dryer into the atmosphere. These dryers are less expensive compared to ventless dryers.
A gas tumble dryer is a type of vented tumble dryer. In this dryer, a gas burner is used to heat the air. This air is passed to the drum. After the water is evaporated, moist air is vented out through the exhaust.
Ventless tumble dryers are dryers without a vent. These tumble dryers condense the moist air and store the water in a water container. These dryers are relatively expensive and efficient.
Ventless dryers also contain a drainpipe. The moist air is condensed into water and stored in a water container. Recall that the user may also opt for a drainpipe to eliminate the process of draining the water container.
There are a variety of ventless tumble dryers on the market.
Condenser Tumble Dryers,
Heat Pump Tumble Dryers, and
Hybrid Tumble Dryers.
Before learning about a vented tumble dryer, we must recall the components. The components of a tumble dryer are:
Drum,
Drum support rollers,
Drive belt,
Idler pulley,
Blower,
Exhaust duct,
Heating element,
Motor assembly, and
Thermostat.
Working of a Vented Dryer
The user can load the clothes into a dryer drum. The baffles inside the drum help the dryer lift clothes and tumble them. The drum sits on a drum support roller.
The motor rotates the drum through a drive belt. An idler pulley puts tension on the belt. A blower sucks the atmospheric air and pushes it towards the heating element.
Then, the heating element heats the air. The heated air passes through the holes on the back of the drum. This air enters the rotating drum and takes the water from wet clothes.
The air becomes moist and passes through a lint filter. A lint filter collects the lint shredded from the clothes and allows the air to pass further. A thermostat placed in an air duct sends the temperature to the heating element to regulate the temperature.
An exhaust duct removes the moist air into the atmosphere. Recall that there are rigid or flexible ducts available in the market.
Working of a Gas Dryer
Next, we may begin with the working of a gas tumble dryer. The components of a gas tumble dryer are almost similar to that of a vented tumble dryer.
Similar to whatever we learned in vented tumble dryers, the components whose working is the same are:
Drum,
Drum Support Rollers,
Motor,
Drive Belt,
Idler Pulley,
Blower,
Exhaust Duct, and
Thermostats.
The gas burner is responsible for heating the air in a gas dryer. This heated air passes into the drum and absorbs the water from wet clothes, removing moist air through a vent.
Working of a Condenser Dryer
Next, we’ll learn about the condenser dryer, a ventless dryer. The working of the drum, drum support rollers, motor, idler pulley, and thermostats are the same.
In a condenser dryer, the exhaust duct is eliminated. The moist air is condensed back to the water, and the air is reused. In this dryer, the blower blows the air into the heating element.
The hot air is passed into the drum. The drum rotates and tumbles the clothes to heat them uniformly. The air gets moist and passes through the lint filter blocking the lint.
The air passes through a condenser. Condensers are devices that convert gas to liquid by exchanging heat.
In a condenser, heat exchange occurs between the hot moist, and cold air. The hot air passes from the front to the rear inside a condenser. Ambient air is sucked from the outside and passed to the condenser for heat exchange perpendicularly.
Inside a condenser, moist air condenses, and the ambient air gets heated up. The cooled air moves further to the blower, and the heated ambient air escapes the dryer. A pump pumps the condensed water into the container.
A drain pipe can drain the water from the dryer to any desired location. The water may drain into the washing machine or the sink.
Working of a Heat Pump Dryer
Next, we'll learn about the working of heat pump dryers. The components of the heat pump dryer are similar to that of the condenser dryer. In addition to the condenser, this dryer contains an evaporator and a compressor. It can also reheat the air, eliminating a heating element.
The hot air evaporates the water from the clothes and passes through a primary and secondary lint filter. It ensures that the lint is not entering the heat pump system. After passing through the secondary lint filter, the moist air enters the evaporator.
Evaporators extract the heat from the moist air. Initially, the refrigerant in the evaporator is in a cold liquid state. After the warm moist air comes in contact with the evaporator, it gets cold, and the refrigerant temperature rises.
The refrigerant enters the compressor. The compressor increases the refrigerant’s pressure and temperature. The high-temperature refrigerant enters the condenser.
The high-temperature refrigerant transfers the heat to the cooled air. It reheats the air and moves to the dryer drum. The refrigerant passes through an expansion device and drops the pressure and temperature.
The low-temperature refrigerant enters the evaporator. Both of these cycles repeat themselves.
Working of a Hybrid Dryer
Next, we’ll learn about the working of a hybrid dryer. This dryer contains a heating element and a heat pump system for heating the air. After the moist air passes through the secondary lint filter, it enters the heat pump system.
The user can select the mode on the controls depending on their requirement. There are generally three modes:
Speed,
Balanced, and
Eco.
The heating element and heat pump system are connected in series in the air circuit.
Speed mode requires more energy; however, drying time is reduced. The balanced mode requires moderate energy and takes moderate drying time. Eco mode requires less energy but drying time is increased.
If a user selects speed mode, the heating element and heat pump system operate simultaneously to heat the air. The moist air passes through a secondary lint filter and enters the evaporator. The evaporator extracts heat from the moist air and cools it down.
The condenser reheats the air and passes through the heating element. The heating element again heats the air and passes it to the drum, and the cycle repeats itself. A heating element and heat pump improves efficiency and reduces the drying time.
The balanced mode requires moderate energy and takes an average drying time. If the user selects balanced mode, the moist air passes through a secondary lint filter and enters the evaporator. The evaporator extracts heat from the moist air and cools it down.
The condenser reheats the air and passes through the heating element. In balanced mode, the heating element remains off. So, the air passes through it but doesn’t get reheated. Then it passes to the drum, and the cycle repeats itself.
Eco mode requires less energy but drying time is increased. If the user selects eco mode, the moist air passes through a secondary lint filter and enters the heat pump system. The heat pump system remains off. So, the air passes through it but doesn’t get heated up. Then air enters the heating element, which heats it and passes into the drum, and the cycle repeats itself.
Ventless dryers are of three types:
Condenser Tumble Dryer,
Heat Pump Tumble Dryer, and
Hybrid Tumble Dryer.
The Condenser Dryer uses a condenser unit to cool the air and a heating element to heat the air. The Heat Pump Dryer uses a heat pump system to cool and heat the air. The Hybrid Dryer uses a heat pump system to cool the air and a heating element to reheat the air.
Working of Tumble Dryers - II
By the end of this module, you should be able to describe:
The Manual and Automatic tumble dryers,
The working of Manual and Automatic tumble dryers,
Differences between various types of tumble dryers, and
The features of a tumble dryer. Skip to quiz!
Manual and Automatic Dryers
All the dryers are available in manual and automatic variants. Manual dryers are equipped with timers and dials that control them. The user has to set the time for drying the clothes.
The dryer stops after the scheduled time is over. These dryers are usually cheaper than automatic dryers. The user may be unable to predict the drying time for a given load, resulting in under-drying or over-drying.
Under-drying occurs when the user enters less time than the required time. Here, the clothes are partially dried and need to be dried again later. Over-drying occurs when the user enters more time than the required time.
In over-drying, the dryer runs even after the clothes are completely dried off. It leads to additional electricity consumption and affects the efficiency of the dryer. Next, we’ll learn about automatic dryers.
The automatic variants are equipped with dryness sensors and thermostats. Dryness sensors are used to sense humidity inside the drum. It stops automatically when the clothes are dried.
Automatic dryers are relatively expensive but are more efficient than manual dryers. These dryers save time and money. The running cost is relatively less compared to the manual dryers.
The automatic tumble dryers come packed with three degrees of dryness for both cotton and synthetic settings:
Iron dry leaves the clothes slightly damp to make ironing easier. The user must iron them as soon as the cycle is finished.
Cupboard dry ensures that the clothes are dry enough to be put away once the cycle has finished.
Extra dry is best for more oversized items such as duvets or pillows as it ensures everything is dry.
Next, we’ll learn about the other settings available on some dryers.
Wool is a delicate material, so woolen clothes are dried on low heat in a Wool setting. Mixed is the setting used while drying a variety of different materials. Some dryers come with a shoe rack, and the shoes will suspend in the middle of the drum as it rotates.
Difference Between Various Dryers
Next, we’ll learn the differences between various types of dryers. In a vented and a condenser dryer, the heating element heats the air. A gas burner is used in a gas dryer and a heat pump system in a heat pump dryer.
The hybrid tumble dryers use both the heating element and heat pump system. Electricity is used as a power source in a vented, condenser, heat pump, and hybrid tumble dryers. In gas dryers, electricity and gas are used as power sources.
The air is reused in a condenser, heat pump, and hybrid tumble dryers. The air is expelled in vented and gas dryers. Moist air is expelled using an exhaust duct in vented and gas dryers.
Moist air is condensed and collected in a water container in a condenser, heat pump, and hybrid dryers.
The initial cost of a gas dryer is the lowest, lower of a vented dryer, high of a condenser dryer, higher of a heat pump dryer, and highest of a hybrid dryer.
The running cost of a condenser dryer is moderate, the gas dryer is high, the vented dryer is higher, the heat pump dryer is low, and the hybrid dryer is the lowest.
The efficiency of Vented and Gas dryers are low. Condenser dryer is high, Heat pump dryer is higher, and Hybrid dryer is highest.
Vented and Gas dryers are not eco-friendly. However, Condenser, Heat pump, and Hybrid dryers are eco-friendly.
Features of Tumble Dryers
Dryers have evolved in the last few decades and are equipped with new technologies. Drum light is provided inside a drum. The user can ensure they haven’t forgotten a cloth in the drum after the drying cycle.
Door options allow the user to place the dryer door on either side of the dryer. Anti-crease ensures the clothes will not be creased until the door is opened. It works by rotating the dryer drum occasionally until the door is opened.
Cool setting is a feature for clothes that don’t require drying but could do with freshening up if they have been in storage for a long time. Self-cleaning helps to keep the drum clean so that the clothes remain lint-free. Also, lint inside the condenser is washed automatically after 4-5 drying cycles.
Status updates have a sensor that detects when your clothes are dry. The dryer notifies the user using an LED or a buzzer whenever the drying cycle is complete. The time delay allows a user to start the drying at a convenient time.
The quiet function has an anti-vibration mode which can help reduce the noise of a tumble dryer so the user can use it at any time of day or night. The features vary from model to model.
All the dryers are available in manual and automatic variants. The user has to enter drying time in a manual dryer. The user has to enter the dryness level they want to obtain in an automatic dryer.
The efficiency of Vented and Gas dryers are low. The efficiency of the Condenser dryer is high, the Heat pump dryer is higher, and the Hybrid dryer is highest. The features of the dryer vary from model to model.
Question #1: What is the purpose of an exhaust duct?
To remove the moist air
To heat the air
To clean the air
To rotate the blower
Scroll down for the answer...
Answer: To remove the moist air
The exhaust duct removes the moist air into the atmosphere.
Question #2: What does an evaporator in a heat pump dryer perform?
It heats the moist air
It cools the moist air
It heats the refrigerant
It cools the refrigerant
Scroll down for the answer...
Answer: It cools the moist air
The evaporator cools the air.
Question #3: What does a compressor in a heat pump dryer perform?
It heats the moist air
It cools the moist air
It heats the refrigerant
It cools the refrigerant
Scroll down for the answer...
Answer: It heats the refrigerant
A compressor heats the refrigerant.
Question #4: Why are the heating element and heat pump included in a hybrid dryer? (Select all that apply)
To improve efficiency
To reduce the drying time
To remove air from the heating element
To reduce efficiency
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Answer: To improve efficiency
To reduce the drying time
A heating element and heat pump are included in a hybrid dryer to:
Improve efficiency.
Reduce the drying time.
Question #5: Why are timers installed in the manual dryers?
To automatically stop the drying cycle
To dry clothes for a particular time
To monitor the temperature of the ducts and pipes
To avoid overheating
Scroll down for the answer...
Answer: To dry clothes for a particular time
The timers are installed to dry clothes for a particular time.
Question #6: Why are dryness sensors installed in an automatic dryer? (Select all that apply)
To automatically stop the drying cycle
To dry clothes for a particular time
To monitor the temperature of the ducts and pipes
To avoid overheating
Scroll down for the answer...
Answer: To automatically stop the drying cycle
To monitor the temperature of the ducts and pipes
To avoid overheating
The dryness sensors are used to:
Automatically stop the drying cycle.
Monitor the temperature of the ducts and pipes.
Avoid overheating.
Question #7: Which of these dryers has the highest initial cost?
Heat pump dryer
Hybrid dryer
Gas dryer
Condenser dryer
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Answer: Hybrid dryer
Hybrid tumble dryers are the most expensive.
Question #8: Which of these tumble dryers is most efficient?
Gas tumble dryer
Condenser tumble dryer
Heat pump tumble dryer
Hybrid tumble dryer
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Answer: Hybrid tumble dryer
Hybrid tumble dryers are the most efficient out of these tumble dryers.
Question #9: The features of the dryer do not vary from model to model.
True
False
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Answer: False
The features of the dryer vary from model to model.