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A solar air cooler works on solar energy. As the name suggests, it uses solar power to meet its energy requirements. Its operational mechanism is different from conventional evaporative air cooler and it better than solar air conditioner. The solar energy from sun is converted into chemical energy and stored in a battery. This battery then acts as the source of power supply for the cooler. Its simple mechanism and economical operation render it as obvious choice for almost everyone. It’s extremely useful for rural areas where there will be no electric supply.

1. Solar Air Cooler’s Working Principle

A solar air cooler makes use of the evaporative cooling mechanism. This is the most cost effective Eco-friendly and efficient cooling method. To understand the basic principle, imagine yourself coming out of the pool in peak summer. When the hot wind touches your body, the water droplets on your skin evaporate. This evaporation leads to reduction of surrounding temperature, thereby making you feel cool and comfortable.

When the cooler’s fan starts operating, outside hot air is sucked inside through the wet curtains (cooling medium). This hot air evaporates the water from the wet pads. The water evaporation reduces the temperature of the air by using up the heat. Therefore, the air blown out by the fan is fresh and cool.

Our in-house produced powerful cooling fans find great utility in several fields like industries, workshops etc. The solar cooler has gained lot of popularity due to its rugged, economical and environment friendly design. It has got an ever increasing demand in the USA, China, Europe, Africa, Middle East, Asia etc.

2 . Solar Cooler VS Air conditioner

 In order to compare solar cooler with an air conditioner, we should understand their basic principles. The following sub-paragraphs bring out the working principles and other relevant aspects for these appliances :

(a) Solar Evaporative Coolers

Solar evaporative coolers also called Solar swamp coolers are not as widespread as the vapor compression (refrigerant) ACs. But they are a great alternative in hot and dry areas with frequent power hick-ups. The hot and arid air is drawn in by the cooler’s fan. The air passes through the cooling pads which are continuously kept wet with the help of a pump. The hot air evaporates water and thus becomes colder. This colder air then gets circulated in the room by the powerful industrial grade fan. The phenomenon is the same as experienced when you come out of a swimming pool. Even the hot air feels cool as the water droplets on your body evaporate. They can reduce the temperatures of your house or workplace by about 30 degrees.

(b) Heat Pump and Central ACs

Heat pumps and Central ACs are designed for cooling the complete hotel, office establishment or house. In both the types of appliances, there’s a compressor that’s placed outside. While this outdoor component drives the system, the indoor unit having refrigerant filled coil cools down the air. The cold air then passes through ducts to reach various parts of the building. The Central AC can only cool the air, whereas a Heat pump is capable of reversing the cycle. This makes it more versatile as it can be used to heat the air during winters.

(c) Room ACs

The wall mounted or window AC units combine the compressor and the coil inside a single body. While fixing, the compressor is still placed outside while the air handling unit (AHU) comes inside. The operating mechanism is the same as that of a Central AC system. They’re smaller in size with power to cool a single room. Hence, a number of such units are needed for the whole house.

(d) Ductless Mini-Split ACs

The mini-split ACs are popular in many countries and are a good alternative for retrofit cases and duct-less houses. They have the same basic principle as that of a Central AC. The mini-split AC has a single outdoor compressor and may have a number of indoor AHUs. These independent AHUs may be mounted on walls or ceiling and are connected to compressor through conduits. Unlike a Central AC system, each zone or room will need a separate AHU.

While AC seemingly provides fast and effective cooling, it consumes more power and is not good for environment. The evaporative cooling system not only provides comparable cooling, but is much less power hungry. When you combine these advantages with benefits of solar power, the resulting system is a true winner.

3 .What is the solar cooler Advantage and Disadvantages

The solar powered cooler has numerous advantages over the air conditioner and other air cooling systems. There are no disadvantages of the cooler, although it has certain limitations. All these are enumerated in the following sub-paragraphs :

Advantages

The solar cooler is a great choice for almost all types of users. It’s ideal for areas where power cuts are frequent or where there’s no electric power. Being available in various sizes, it suits industrial usage as well as individual household use. Some of the most noted benefits of the Solar cooler are :-
  • It uses solar energy and has minimal running cost.
  •  It saves electricity and has no carbon footprint, which makes it highly Eco-friendly.
  •  It’s easy to use and handle with simple design.
  •  With simple and cheap components, it has very less maintenance expenses.
  •  It’s initial cost is quite low.

Limitations

The only limitation of the solar air cooler is its dependence on solar energy. This makes it likely to be affected by weather conditions. It can not be used effectively in cloudy conditions. But then, you don’t generally need a cooling system in overcast weather.

4. Where is the solar cooler application 

 It can be used in the rural areas where power cut is a problem.

Área de aplicação de climatizador evaporativo

5.What is solar cooler Features

Solar Panels

A set of photovoltaic cells connected electrically and fitted on a supporting frame constitute a solar panel. These cells convert sunlight into electricity using photovoltaic effect. Most modules use either crystalline silicon cells like wafer or thin telluride/silicon based cells. The modules may be rigid or semi-flexible in nature and physical damage. The load bearing member of the module may be placed at the top or bottom. The cells need to be protected from elements of the nature. Earliest recorded use of solar modules was in 1958. Modern developments in the field include use of lenses and mirrors as concentrators and micro-inverted solar panels etc. Micro-inverted cells connected in parallel ensure that each panel gives maximum possible output under the given conditions. Therefore, costly cells like gallium arsenide can be used in a much more cost-effective manner.

Battery

Battery

 A dry cell which is the common battery converts chemical energy into electrical energy. These are commonly used in many devices like cameras, hearing aids, toys, remote controls, torches etc. The outer zinc case acts as the negative electrode or cathode, which is filled with electrolyte paste. Grounded carbon, manganese dioxide, zinc chloride etc are used as electrolyte. The positive electrode or the anode is the carbon rod that’s placed in the centre of the cell. The flow of electrons in the circuit from cathode to the anode through electrolyte generates electricity.

 

Charge Controller

A charge controller or a battery regulator regulates the current flow. By controlling current flow into the battery, overcharging is avoided, thereby enhancing battery’s performance and providing safety. It also avoids complete discharge of the battery and hence increases its life. A charge controller may be either a stand-alone device or an internally integrated circuit within the battery-powered equipment. There are terminals with screws at the base of the solar controller. These terminals are marked with positive (+) and negative (-) signs for ease of identification.
Note : It’s very important to have proper connections. The polarity should be correctly joined keeping the +/- terminals in mind. Incorrect battery connections may lead to damages to the appliances, solar panel or the battery. Following steps should be taken to ensure proper connections :
Step 1 : Battery Connection
Connect the battery to the charge controller using suitable cables. It is recommended to connect a fuse near the battery’s positive (+) terminal.
Step 2 : Solar Panel Connection
Ensure that the solar panel and the battery are of the same voltage. Study the specifications and manufacturer’s guide before commencing connections. There are clearly marked ‘SOLAR PANEL’ terminals on the solar controller. Connect the solar panel to these terminals using appropriate cable as per manufacturer’s directions. Before switching on the circuit, check that the solar panel is correctly connected. This can be done by scrolling through the settings to view input voltage of solar panel.
CAUTION : Solar panels always generate electricity when exposed to the sun. So, handle these with care even when disconnected. If the connection gets completed accidentally, electric shocks may result. It may cause serious injuries to handlers or may result in fire. It’s therefore highly recommended that the front portion of solar panels are covered during installation. They may be covered using some soft cloth to block sunlight to avoid current generation.
Step 3 : Solar Cooler Connection
The final step is the connection of the solar cooler to LOAD terminals of the solar controllers.

PMDC Motor

motor

Permanent Magnet DC (PMDC) motors were first introduced in the 19th century, but were not widely accepted. The main rea
son for this was the poor quality of magnetic materials like tungsten steel available at that time. This put a limitation on the efficacy of the PMDC motors. This diverted the motor designers of that era towards motors in which electromagnetic fields were used for excitation. Thus electromagnetic motors acquired the centre stage of all new developments until recently. Advancements in magnetic technology demonstrated improved power density and steady state performance of PMDC motors. There has been a sharp increase in the demand of these motors in the global markets. PMDC motors are widely being used in various appliances like medical instruments, office equipment, computer peripherals etc.

There are numerous benefits of the PMDC motor over its DC counterpart. Five of the major advantages are as under :

  • Higher efficiency. Unlike a DC motor, in which electricity is used to maintain a magnetic field, there are no losses in a PM motor. This means that the PMDC motor has a higher efficiency.
  •  PMDC motor has higher torque power density.
  •  The motor has more predictable characteristics because of linear torque speed.
  • PMDC motor has higher magnetic flux density in the air gap due to its permanent magnet. This enables it to have better dynamic performance.
  • Simple design of PMDC makes it easy to maintain.

6.How much do the solar evaporative cooler lower the temperature

Being a solar powered cooler, it’s generally good for all as it saves electricity and is Eco-friendly. However, an evaporative cooling system works best in areas having low relative humidity. It’s known to lower the temperatures to around 20 degrees Celsius. It’s cooling efficiency goes down with increasing relative humidity. You must therefore check the relative humidity of your area during summers before buying it. As a thumb rule, if the air produced is cooler than 70 degrees Fahrenheit, the cooler will be useful. If the air produced is hotter than 75 degree Fahrenheit, it won’t be of much use. 70-75 degrees Fahrenheit is the range in which some people will feel comfortable, whereas, the others may not.

Portable Evaporative Cooler

7. What factors affect solar powered cooler temperature

In order to understand the cooling efficiency of the evaporative cooler, we must first understand its cooling concept. The cooling concept of an evaporative cooler is that hot air loses energy due to evaporation of water. The extent of cooling achieved depends on the following two temperatures :

Dry Bulb Temperature (DBT)

Commonly called the air temperature, this is the reading obtained on a thermometer directly exposed to air.

 Wet Bulb Temperature (WBT)

Air is passed over a thermometer with its bulb covered by a water soaked cloth. The temperature measured in this thermometer is called the WBT.
the different between Dry Bulb Temperature and Wet Bulb Temperature

What is the different between Dry Bulb Temperature and Wet Bulb Temperature?

The difference between the values of WBT and DBT is a measure of the potential cooling that can be achieved by an evaporative cooler. These values in turn depend upon the relative humidity of the air. Humidity implies the amount of water vapor that’s already present in the air. Ratio of this value to maximum amount of water vapor that air can hold is called relative humidity. Air can evaporate water only till the relative humidity is below 100%. The extent of evaporation and hence cooling also steadily keeps reducing as this value increases. As the hot and arid air passes through the cooling pads of the cooler, it gives its heat to water which evaporates. This lowers the DBT of the air but also increases its relative humidity. The air is cooled only to an optimal level and thereafter the temperature balance is maintained. This is the reason that unlike an AC, an evaporative cooler will not have a chilling effect

8.How to Calculate solar air cooler running time

Solar air cooler

Here our cooler load voltage is 12V and the total wattage is 120.

Battery capacity is 12V, 100Ah

Solar panel is 18V,200 W

Solar cooler running time = Battery current(A)/ Solar panel current(A)

Solar panel current(A) =watt / volt

Time need to charge only by solar=100/(200÷18) = 9 hours

So the solar air cooler running time is 9 hours

Note: Combination of external sources and solar panel will reduce the charging time. (All assumptions are made neglecting all losses)

9.How to Calculate the Payback for solar cooler

 Payback is defined as the amount of time in which our product becomes free

Let’s suppose that:

The full set of solar cooler including solar accessories is USD400, We will use 8 hours per day and use 120 days per year,The electricity charge is USD0.15/Kw-hour

So:

If we use air conditioner to cool the space, it will take us 8*120*1*0.15=USD144 per year

Now:

We use solar air cooler instead, we will get the money back in 2.78 years (400/144)

It means that after 2 years and 284 days,you will get all your money back and you own the solar air coolers for free after that. Moreover,it will keep saving electricity bills for you after that time. 

Note: If we use air conditioner to cool the space instead of solar air cooler,we might need 1 Kw/h electricity

10.Top tips to choose the right solar air cooler brand

Low price, minimal operating costs and cheap maintenance make solar cooler an affordable choice for all. It’s excellent for rural and backward areas where electric supply is not there. It’s a favorite in schools, houses, offices and workplaces in areas of frequent power cuts. It cools down the room temperature to a comfortable 20-25 degrees Celsius with relative humidity of 60%.

For any dealer wishing to buy the coolers in bulk, choosing a manufacturer with the most competitive prices is recommended. Vankool is a superb choice for those in the wholesale business. It is the preferred OEM dealer for Honeywell for the past 12 years.

solar cooler

Vankool who can meet such requirements and will be a good choice when you consider to choose a window swamp coolers manufacture in China.  Here 6 more reasons that why Vankool could be a good choice for you:

– Over 12 years experience in the field of evaporative air coolers

– Vankool OEM supplier for Honeywell for more than 12 years.

– Over 5 new air coolers will be designed for customers by ODM service

– With full range of evaporative air cooler products like portable air coolers (residential and commercial), window air cooler, industrial air cooler

– ISO 9000 QC standard will be applied for each order

– Short delivery time for sample order (1-2 days) and bulk order (15-25 days)

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