Alfred Ajibola
- 19th September, 2019 @ 3:34 PM
Topics in Basic Technology
Definitions of technology and their explanations Examples of technology Forms of technology explained with their differences Types of chain drive Types of belt drive Types of Ceramics Advantages and Disadvantages of Chain Drives Len Academy Questions for Basic Technology JSS3, 2nd Term Len Academy Basic Technology Questions, JSS3 Belt and Pulley Drives: Types of belt in belt drives Refrigerator as an electromechanical device, its parts and operations What is chain drive? Classification of chain drive What are Belt Drives? Advantages and Disadvantages of Belt Drives Type of Lines in Technical Drawings Len Academy questions for Basic Technology, JSS2, 2nd Term Len Academy questions for Basic Technology JSS2, 2nd Term, Part 2 What is Maintenance? Types of Maintenance Hardwood and Softwood - Characteristics and Examples What are Ceramics? Characteristics of CeramicsAcademic Questions in Basic Technology
The _____ functions to remove excess heat from the refrigerator.
A. Evaporator
B. Compressor
C. Condenser
D. Expansion Valve
E. Thermostat
F. Defrost System
A fluid or gas that runs through the compartments of a refrigerator is termed _____.
A. Water vapor
B. Liquid vapor
C. Frost
D. Refrigerant
E. Compressed water
F. Evaporated water
Current flows through a path called _____.
A. Electricity
B. Electric Route
C. Electrolysis
D. Transformer
E. High Tension
F. Electric Circuit
Googles are safety wears.
A. True
B. False
Which of the following is false concerning advanced ceramics?
A. They can be made from metallic oxides
B. They are very hard and durable
C. They are corrosion resistant
D. They are fired in the presence of oxygen
E. They are fired at a very high temperature of about 1700oC
F. They can be made from non-oxides such as carbides and borides
A thin continuous line is used for representing the followings except _____.
A. Intersections
B. Hatching lines
C. Long breaks
D. Diagonal line used to state plane surfaces
E. Leader lines
F. Back section lines
With regards to chain drives, the diagram above is a/an _____ chain.
A. Roller
B. Silent
C. Leaf
D. Flat-top
E. Detachable
F. Acceleration
A type of chain drive commonly used in bicycles is the _____ chain.
A. Roller
B. Silent
C. Leaf
D. Flat-top
E. Detachable
F. Acceleration
Electromechanical energy consists of two forms of energy. These are:
Electrical Energy
Mechanical Energy
Electromechanical energy refers to the conversion of electrical energy into mechanical energy or vice versa (mechanical energy to electrical energy) as seen in various appliances. The refrigerator is a typical example of an electromechanical device.
Devices that make use of electromechanical energy are called electromechanical devices. They include the refrigerator, air conditioners, loudspeakers, microphones and so on.
In this article, we will explore on the refrigerator and it’s mechanism of operation.
You can read on chain drive here.
The refrigerator comprises of both the fridges and deep freezers. They function to serve the storage of edible materials and other substances. Also, drinks are kept cold for the satisfaction of people via the refrigerator.
Meanwhile, medical and chemical industries use the refrigerator to preserve drugs and other important chemicals at a temperature in which the various micro-organisms that brings about their decomposition are unable to act.
Please read on micro-organisms causing food, water and air borne diseases here.
Below are some of the major parts or components that make up a refrigerator:
Refrigerant
Evaporator, Freezer or Chiller
Compressor
Condenser
Expansion Valve or Capillary
Thermostat
Defrost System
The diagram below shows the major components of a refrigerator:
The refrigerant can be a liquid (fluid) or gas (vapor), and it runs throughout the various tubes or compartments of the refrigerator.
The refrigerant (fluid in this instance) flows throughout the entire pipes of the refrigerator. This fluid refrigerant expands from its liquid state into a vapor state. This implies that it changes into vapor refrigerant since it takes in heat from its surroundings, thus bringing about the cooling processes inside the fridge or freezer.
The refrigerant (fluid) absorbs heat from the substances to be cooled (present in the evaporator). As a result, the fluid refrigerant becomes vapor.
Conversely, the condenser condenses the refrigerant (vapor) into liquid (fluid refrigerant). This process will be explained in a latter part of this article.
Both aformentioned processes repeats itself in cyclical manner; and is referred to as the refrigeration cycle.
Please read on thermal equilibrium and zeroth law of Thermodynamics here.
The evaporator is the cooling chamber where food materials are kept in the refrigerator. It acts by extracting heat from the food items in order to bring about their coldness.
The evaporator is a heat exchanger. It is made up of several turns of coil made of aluminium or copper. The evaporator simply refers to the coil in the refrigerator where cooling and freezing is achieved.
It is within the evaporator that the refrigerant absorbs the heat from the substance to be cooled.
The evaporator is also called the freezer or chiller.
Please read on heat transfer here.
The compressor of a refrigerator is always seen at the lower back region of the refrigerator. It is the mechanical section of the refrigerator in which the refrigerant is compressed into a vapor state.
The compressor acts by sucking the gaseous or vapor refrigerant from the evaporator, while also releasing it at a high temperature and pressure.
The sucking or pumping action of the compressor occurs from the low pressure evaporator to the high pressure condenser.
The circulation of the refrigerant in the refrigeration system is brought about through the pumping action of the compressor.
Meanwhile, understand that the compressor is driven by an electric motor which makes it the major power consuming part of the refrigerator.
The condenser comprises a series of arranged pipes or (coils of copper tubing) at the lower posterior end of the refrigerator, from where heat is lost to the atmosphere.
The compressor pumps the refrigerant into the condenser where it is cooled by atmospheric air. The condenser thus absorbs heat through the aforementioned process. Since heat is extracted by the condenser, it becomes very hot as a result.
The condensation of the gaseous refrigerant occurs in the condenser. This simpy means that the refrigerant changes its state from vapor to liquid (fluid) within the condenser. In short, the condenser condenses the gaseous refrigerant, that is: it changes the refrigerant's state to from gas to liquid.
Please read more on the states of matter here.
The refrigerant that leaves the compressor is now a liquid. As the liquid (fluid) refrigerant flows, it becomes expanded on its path towards the evaporator. This expansion process causes the liquid refrigerant to evaporate into its gaseous state (in the evaporator).
As soon as the gaseous refrigerant enters the capillary or expansion valve, its temperature and pressure drops, as it cools again. This cooling refrigerant cools the evaporator as it flows through the pipes in the evaporator.
The expansion valve is also called the capillary.
This is the temperature controlling device on the refrigerator. Recall that temperature is the degree of hotness or coldness of a body.
Please read on the concept of temperature and heat here.
The thermostat consists of a sensor connected to the evaporator. The (settings) on the button of the thermostat can be adjusted in the compartment of the refrigerator where it is located.
If the set temperature (on the thermostat) is reached within the refrigerator, the thermostat shuts down the power supply to the compressor. This results in a reduction of temperature in the refrigerator. To this end, you may have observed a stoppage in the function of the refrigerator (similar to muting a sound). After some time, the refrigerator resumes its activity (similar to starting its sound).
Please read on the internet of things here.
As the name implies, the defrost system of the refrigerator functions to remove excess ice from the surface of the evaporator.
The thermostat button can also be used to achieve this function when it is pressed.
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Amazing facts in Basic Technology
Rubber bands last longer when refrigerated
Lighter was invented before matches
Johann Wolfgang Dobereiner was credited with the invention of lighter in 1826 while the match was made 3 years later
Volkswagen group of companies own some of the top cars of the world. These are Audi, Bentley, Bugatti, Ducati, Lamborghini and Porsche
Notable points in Basic Technology
Arrowhead lines are lines with pointed edges at one or both ends. The pointed edges are in the form of an arrow.
Arrowhead lines are used:
At the end of dimensional lines.
As measurement lines.
A thin continuous line could be a straight or curved line. However, the main point to remember is this: 'it is a tiny line with no dot or dashes within it'.
_______________________
A thin continuous line is used for representing the followings:
Projection lines
Hatching lines
Construction lines
Short center lines
Measurement lines
Diagonal lines used to state plane surfaces
Intersections
Leader lines
Backside section lines
Any action that involves the servicing, checking, replacing and repairing of an equipment, object or device is termed maintenance.
Maintenance has two main goals. These are:
To prevent a breakdown
To repair the breakdown
Below are the types of maintenance:
Preventive maintenance
Corrective maintenance
Predictive maintenance
Periodic maintenance
Reinforcement
Overhaul
Softwoods are often derived from coniferous trees, that is: trees with needle-like leaves, and whose seeds are covered in cones.
Below are some characteristics of softwood:
Most softwood have lower densities than hardwood (weighs lower).
In terms of price, they are often less expensive than hardwood.
Their growth rate is faster than hardwood.
Most softwood do not shed their needle-like leaves during the year. However, the softwood 'larch' and 'cypress' are exceptions.
They are less fire resistant.
The diagram below shows the various types of line in technical drawing, their description and general application:
Please read more on the types of line in technical drawing here