How to select the best air purifiers for Home use.

The presence of airborne contaminants in big cities and small towns due to a number of factors like dust, dirt, automobile fumes, pollens from flowering trees and plants, pollutants from industrial activities have given rise to a number of breathing disorders and illnesses and necessitated the use of air filters or air purifiers in every household. These air purifiers considerably check the menace of airborne contaminants and considerably improves indoor air quality. Even though the use of industrial air purifiers in processing plants and factories is very common, but home air purifiers have recently become very popular owing to a rise in concerns over the deteriorating air quality indoors and outdoors. In this topic, I am underlying the basic parameters over which we can base our selection for the best air purifiers for home use.

Working Principles of a Home air purifiers.

Commonly there are two types of air purification processes in any air purifier.

Active Air Purifiers-- In these air purifiers, negatively charged ions are released in the air by purifiers due to which dust and dirt particles sticks to the surfaces which can further be wiped daily by manual methods

Passive air purifiers-- In these types of air purifiers, which are effective and cheaper also, dust and pollutants in room air are filtered through a series of layered filters. 

            1.    HEPA Filters --Since 2005 most common filtration method is through the use of HEPA                           (High- efficiency Particulate Air) filters. These filters effectively remove at least 99.97                           % of                       0.3-micron particles and are usually more effective at removing larger                       and smaller particles.

            2.    MERV  Filters-- These are commonly used in Industrial HVAC attached air filters. Even                        though capture rate of these filters is less than HEPA Filters, but it considerably filters                              more   air in a given time scale.

Additionally  UV filters and activated carbon filter layer is also provided in modern-day air filters.

How to select the best dishwashers for Indian cooking. 

In this blog post, I am trying to simplify the process of selecting the best dishwashers for Indian cooking as Indian cooking is the most complex in the world. 

Washing utensils after every meal is a nightmare for everyone who is entrusted with this work that too in an Indian Kitchen. Indians use a lot of fats, oils, and spices, and also their utensils are in very diverse shapes and sizes. Indians use a variety of dishes, bowls, Tawa, patellas, and Kadai to name a few. In addition to this regularly they cook a variety of full meals involving a number of utensils and implements. Hence for the sake of comfort and hygiene, it is advisable that one should use a dishwasher machine for washing utensils. It is a very clean way of washing utensils in less time and effort. Also, it makes our kitchen much tidier. In these circumstances choosing the best dishwashers for Indian cooking involves a lot of searches and comparisons. Even though a number of dishwasher brands are available in the Indian market, but choosing a dishwasher that has adapted to Indian conditions is a cumbersome search. Even though dishwasher technology is a very old technology involving a stream of water jets, Indians were not using these machines in vast numbers. But nowadays it is making its presence in Indian kitchens particularly in middle-class households.

Based on household needs dishwashers are available in a variety of sizes and layouts. Even though dishwashers for commercial use are available and frequently being used in restaurants and big commercial units, here we are interested in comparing and selecting the best dishwashers for Indian cooking in homes.

Working of home-use modern dishwashers.

Dishwashing machines may be stand-alone or installed in a cabinet, but the working principle remains the same. Almost all dishwashers use strong water jets sprayed from synchronized rotating jets(propellers) installed inside the machines at the bottom and top which rotates due to water pressure. Dishes and utensils are placed in the machine having a bottom bucket with a heating element for heating the water as per the washing program and this element is also used for drying the utensils. Detergent is added to the water from detergent dispensers. Additionally, water softeners are provided into modern-day machines. These days machines can be programmed for varying the intensity of washing and also for a delayed start. Rinse aid, if separately injected helps in quick drying. Modern-day dishwasher detergents come with rinse aids.

Selecting the best dishwashers for Indian cooking may be based on size, multi-place utensil settings, availability of multi washing intensity programs, consumption of water and energy ( water efficiency and energy efficiency), and warranty of equipment which must include rust warranty along with the price of the equipment. Additional features may be salt indicators and rinse aid indicators.

 Washing machines are must-have home appliances that every middle-income or higher-income household needs today for washing laundry with the help of detergent and water. The availability of washing machines has made handwashing a thing of the past and introduced comfort in the life of Indian women. Washing machines these days are extremely efficient machines having many top-of-the-line features and make the job of washing clothes a lot easier. Moreover, a lot of precious water is also saved. Washing machines these days come either in fully automatic or semi-automatic configuration and are either front load or top load. Generally, front-loading machines are fully automatic and are energy efficient. Prices of washing machines have come down considerably as modern machines no longer require costly gearboxes. Instead, speed control is done using electronically. Manufacturers have considerably reduced vibration due to the use of spring suspensions and hydraulic suspensions. Machines these days come with direct drive motors thereby doing away with the pulley, belt, and tensioners.

Modern washing machines come in a variety of sizes, speeds, capacities, and costs. In addition to these washing machines come in a variety of features like

• Some washing machines come with water jet sprayers and steam nozzles and also have hot water washing features.
• Some washing machines have special purpose drums for washing the clothes using centrifugal and rotating features.
• Modern-day washers can take care of calcification due to hard water.
• Almost all modern-day washing machines come with dispensers.
• Some machines have pulsators instead of agitators for shaking off the dirt and dust off the clothes. 
• Almost all modern-day machines come with electronic logic circuitry for the efficient wash cycle.

Types of modern-day washing machines.

Broadly categorized, modern-day washing machines are

Top Loading and Front Loading, automatic or semi-automatic.

Working of Top Loading Washing machines---Top-loading machines are vertical axis rotating machines having a finned agitator in a perforated basket that is covered within a drum. During the washing cycle, the agitator rotates in a direction and then reverses direction periodically and uses centrifugal force and gravity for the best wash. Top-loading machines are convenient to load, require less maintenance, and cheaper in cost.

Working of Front Loading Washing machines---Front-loading machines are horizontal-axis rotating machines and are in demand commercially or for high-end domestic use. Inner perforated drum and outer jacket drum are placed horizontally. Gravity and back and forth motion of drum is used to achieve agitation. These are simply designed machines and the central axis of the rotating drum is propelled using a motor and a pulley. Suspension of the inner drum and clothes inside an outer drum is a complex arrangement as the weight of the inner drum and clothes is a cantilevered mounting on the outer drum.

Advantages of Front loading machines over top-loading machines.

• Front-loading machines usually use less energy, water, and detergent compared to the best top-loaders.
• Front-loading machines offer better spin-dry efficiency.
• Front-loading machines may be placed in compact spaces.
• Top-loading machines are prone to wear and tear due to the placement of drums on the central axis vertically.
• 
  

How to select the best inverter air conditioner for Home and office use in 1.5 Ton category.

A typical air conditioner is an electrical machine from the family of HVAC systems, that is used to control and regulate heat and humidity from an enclosed area. Additionally, in modern-day air conditioners,  a salient feature of dust control is also provided sometimes. An air conditioner typically uses a compressor for vapor- compression refrigeration.

There are various types of air conditioners typically used commercially these days.

Central Air conditioners

To cool a large building/area having one or multiple rooms, a central air conditioning plant with preferably a liquid cooling agent like water is used in chillers. These units may be ducted or non-ducted as the case may be. 

Split Air conditioners

These are small air conditioner units meant to cool a small room or two. These air conditioners are having two units, an indoor unit, also known as an evaporator unit, and an outdoor unit known as a compressor unit.

Window Type Air conditioners

These are small air conditioners, used for cooling a small room and are having a single evaporation and compression unit, typically mounted on a window frame. These are ductless units.

Portable Air conditioners 

These are a type of split air conditioners where indoor units are portable and connected to the outdoor unit through flexible pipes. These air conditioners are generally installed in temporary structures 

Split air conditioners can be further divided into two basic categories as defined below on the basis of working principles.

Noninverter Air conditioners 

These air conditioners work on the principle of vapor compression refrigeration cycle using only non-inverter motors having single-speed and which operate at full speed till it stops when the desired room temperature is achieved. It automatically starts against when the room temperature drops below desired (set) room temperature. So these non-inverter airconditioners start and stop a number of times during whole working hours of the air conditioning unit and thus consume extra electricity at each start as starting current of air conditioners motor is sufficiently high.

Inverter Air conditioners

These are new technology air conditioners based on a different principle of working.  Air conditioner compressor motors use variable frequency sensors which control the speed of the motor according to the room temperature and adjust to variable speed. As the compression unit never stops and hence energy is saved as there is only a single start of the motor during each working hours.

Which is the best air conditioner--- Inverter or Noninverter

Keeping in view the soaring energy costs, it is advisable that one should buy inverter Air conditioners as these operate on 25-30 percent less energy and cools the room with minimum sound and vibration. Additionally, as the inverter Air conditioner uses variable-speed motors and its motor never stops, it cools the room at a fairly constant temperature throughout the working hours. But inverter air conditioners are a bit costly as the product is still not matured enough to bring down the costs. Moreover, as these air conditioners use complex circuitry and hence maintenance is costly. But these drawbacks are fairly taken care of by a very low energy bill. 

New Age Tech Guru - Solar irradiance and its measurement

 

    Part of a series in renewal energy technologies brought by  M/s Paavi Solar

    

Friends, from the next blog onwards we are going to learn the designing part of Solar PV System. So in this blog, I want to focus on solar irradiance and its measurement as understanding this topic is extremely important for  proper design of the system. In one of the previous blogs, the irradiance curve was explained.  In radiometry, Irradiance is the power per unit area of incident electro-magnetic the radiation falling on a  surface and is measured in watts/m2. In photometry irradiance is known as the amount of light energy falling on a surface per second, weather directly or diffused or reflected, and is measured in watts/sq. mtrs. and denoted by E_e where subscript _e denote energy. Technically speaking it is the light (not heat ) of the Sun which is incident on a solar panel. In laboratory conditions, the irradiance of 1000 watt/sq.mtrs is chosen as test conditions. It is worthwhile to mention that irradiance varies seasonally as well as during the time of the day and hence to know the average irradiance, an irradiance map has been plotted taking into account historical data. Simultaneously placement of Solar panels also affects the amount of Solar radiation falling on the panel.

How much Solar Radiation is available in my area.

Solar irradiance maps based on historical data are available on a monthly average basis for the entire world on a location basis and are freely available on the internet. Also, design software carries an irradiance map as a tool and can generate irradiance data and angle of placement of solar PV panels for maximum radiation at the click of a button. We can easily differentiate between sunshine hours and usable irradiance based on these tools. While designing the system, this data is important for system sizing. Manually also one can measure solar radiation for different times and dates of a month for the location of the System.

 

How to measure Solar Radiation

Solar radiation is measured using an instrument called Pyranometer which has its name derived from the Greek word of “Pyr” meaning fire and “ano” meaning sky. It is a sensor-based instrument that measures solar radiation in Watt/m² and has a field of view of 180⁰. For the measurement of solar radiation, the directional factor is important and so the pyranometer needs to have a directional response to the incoming beam. Pyranometer measures only the light part of sun rays. For measuring the heat part we have pyrheliometers.                                                                               - G P BOSE                                  

 

New Age Tech Guru- Net Metering and Net Meter

 

Part of a series in renewal energy technologies brought by  M/s Paavi Solar

 

Friends, we are continuing to learn Rooftop Solar PV System components. As you are aware that there are three types of Rooftop Solar PV System i.e.

1.     Off-Grid Solar Rooftop PV system

2.     On-Grid Solar Rooftop PV System

3.     Hybrid Solar Rooftop PV System

Out of these, systems at S.N.2 and S.N.3 are primarily installed for lowering the electricity bills and we have already learned it in my previous blog.

Now today, we will learn about Net Metering and Net meter. Net metering is a billing mechanism whereby net credit of electricity added(Export) to the Grid by the Solar PV Generator is given. Suppose a Solar PV resident is generating more energy than required in the day time, extra energy is added into the Grid and this energy is metered in Net Meter and reflects as Exported and the Net Metering bill will have an Export Reading column. During the night or sometimes in daytime also, when a customer uses  Grid Electricity, then the incoming Grid electricity is also metered and reflects as import and Net Metering bill will have an Import Reading Column. On the basis of electricity consumed, a net credit is given to the customer if exported electricity units are more than the imported electricity units. Similarly, if the electricity consumed(imported) from the Grid is more than exported electricity, than the customer has to pay for the net electricity consumed. Hence Net Meter is a bi-directional metering device (approved and supplied by DISCOMs as per policies) for calculating the difference of outgoing and incoming electricity units. It may be added here that while providing Net Meter, DISCOM will test your installation for Grid Compatibility and Synchronization (already stated in one of my previous blogs). Meter reading is shown in BSES Delhi Net Metering bill is classified into three categories of Normal, Peak, and off-peak and then the difference is moderated for billing purposes.

-          G P BOSE

New Age Tech Guru - Cables and Connectors

 

Part of a series in renewal energy technologies brought by  M/s Paavi Solar

 

Friends we have come afar in knowing the components of the Rooftop Solar PV System. Today s topic is very small but important ie Solar connectors and cables.

Solar panels are connected with each other or to the solar panel combiner boxes through D.C. Cables and MC4 Connectors.

MC4 Connectors- These connectors are used for connecting solar panels or for terminating onto solar combiners boxes. MC in MC4 stands for multi-contact and 4 stands for 4 mm dia. For forming the panel strings by inserting adjacent panel connectors, MC4 connectors come in various models like One way, two-way (two in one out), three-way (three in one out), and four-way (four in one out).MC4 connectors can withstand a voltage of 1500V and are rain and dustproof  (weatherproof). These connectors have plug and socket designs (to minimize wrong connections and covered under a plastic shell. The male connector can be inserted into the female connector up to a notch where it gets attached under a spring pressure to prevent the arc from D.C. These MC4 connectors are an up-gradation over previous MC3 (3 MM dia.) connectors in design and assembly.

D.C. Cables- Solar D.C. cables are used to connect individual solar panels to form strings or used to terminate panels into combiner boxes. These single core pure copper cables are insulated (flame-retardant and halogen-free) and sheathed and can have UV protection/ozone protection as these are used outdoors. These cables can be used for fixed or flexible installations. These cables should have standard electrical/physical/mechanical/chemical/Fire safety specifications. Different D.C. cables are used for outdoors and indoors. For outdoor use D.C. must be treated with UV Stabilizing compound and preferably insulated and sheathed with Cross Linkable LSOH which has UV as well as Ozone protection properties, otherwise, indoor D.C. cables can have XLPE insulation.

A.C. Cables- Connection between inverter to Grid/ switching station and to loads are through A.C. cables and if to be laid underground must be armored and if exposed to Sunlight must be UV protected also

 

-         G P BOSE