Most of all, in the frosty winter months, all people are waiting for the New Year, and least of all - receipts for heating. Especially disliked by their inhabitants apartment buildings, which themselves do not have the ability to control the amount of incoming heat, and often the bills for it turn out to be simply fantastic. In most cases, in such documents, the unit of measurement is Gcal, which stands for "gigacalorie". Let's find out what it is, how to calculate gigacalories and convert to other units.
What is called a calorie
Supporters healthy eating or those who strenuously monitor their weight are familiar with the concept of a calorie. This word means the amount of energy received as a result of the processing of food eaten by the body, which must be used, otherwise a person will begin to recover.
Paradoxically, the same value is used to measure the amount of heat energy used to heat rooms.
As an abbreviation, this value is referred to as "cal", or in English cal.
In the metric system, the joule is considered the equivalent of a calorie. So, 1 cal \u003d 4.2 J.
The importance of calories for human life
Besides developing various weight loss diets, this unit is used to measure energy, work and heat. In this regard, such a concept as "calorie content" is common - that is, the heat of the combustible fuel.
In most developed countries, when calculating heating, people no longer pay for the amount of consumed cubic meters of gas (if it is gas), but for its calorie content. In other words, the consumer pays for the quality of the fuel used: the higher it is, the less gas will have to be consumed for heating. This practice reduces the possibility of dilution of the substance used with other, cheaper and less caloric compounds.
What is a gigacalorie and how many calories are in it?
As the definition suggests, 1 calorie is small. For this reason, it is not used for calculating large quantities, especially in power engineering. Instead, a concept such as a gigacalorie is used. This is a value equal to 10 9 calories, and it is written as an abbreviation "Gcal". It turns out that in one gigacalorie one billion calories.
In addition to this value, a slightly smaller one is sometimes used - Kcal (kilocalorie). It holds 1000 calories. Thus, we can assume that one gigacalorie is a million kilocalories.
It should be borne in mind that sometimes a kilocalorie is recorded simply as "feces". Because of this, confusion arises, and in some sources it is indicated that 1 Gcal - 1,000,000 calories, although in reality it is about 1,000,000 Kcal.
Hecacalorie and gigacalorie
In the energy industry, in most cases, it is used as a unit of measurement, Gcal, but it is often confused with such a concept as "hecacalorie" (aka hectocalorie).
In this regard, some people decipher the abbreviation "Gcal" as "hecacalorie" or "hectocalorie". However, this is wrong. In fact, the above-mentioned units of measurement do not exist, and their use in speech is the result of illiteracy, and nothing more.
Gigacalorie and gigacalorie / hour: what's the difference
In addition to the fictitious value under consideration, such abbreviations as "Gcal / hour" are sometimes found in receipts. What does it mean and how does it differ from the usual gigacalorie?
This unit of measure shows how much energy was used in one hour.
While just a gigacalorie is a measure of the consumed heat for an indefinite period of time. It depends only on the consumer what time frames will be indicated in this category.
Reduction of Gcal / m3 is much less common. It means how many gigacalories you need to use to heat one cubic meter of a substance.
Gigacalorie formula
Having considered the definition of the value under study, it is worth finally learning how to calculate how many gigacalories are used to heat a room during the heating season.
For especially lazy people on the Internet, there are many online resources where specially programmed calculators are presented. It is enough to enter your numerical data into them - and they themselves will calculate the amount of consumed gigacalories.
However, it would be nice to be able to do it yourself. There are several formula options for this. The simplest and most understandable among them is the following:
Heat energy (Gcal / hour) \u003d (М 1 х (Т 1 -Т хв)) - (М 2 х (Т 2 -Т хв)) / 1000, where:
- M 1 is the mass of the heat transfer substance that is supplied through the pipeline. Measured in tons.
- M 2 is the mass of the heat-transfer substance returning through the pipeline.
- T 1 is the temperature of the coolant in the supply pipeline, measured in Celsius.
- T 2 is the temperature of the coolant returning back.
- Т хв - temperature of the cold source (water). Usually equal to five because this is the minimum water temperature in the pipeline.
Why do housing and communal services overestimate the amount of energy spent when calculating for heating?
Carrying out your own calculations, it is worth noting that housing and communal services slightly overestimate the standards for thermal energy consumption. The opinion that they are trying to earn extra money on this is wrong. Indeed, the cost of 1 Gcal already includes services, salaries, taxes, and additional profit. This "surcharge" is due to the fact that when hot liquid is transported through a pipeline in the cold season, it tends to cool down, that is, inevitable heat loss occurs.
In numbers, it looks like this. According to the regulations, the temperature of the water in the pipes for heating must be at least +55 ° C. And if we consider that the minimum water temperature in power systems is +5 ° C, then it must be heated by 50 degrees. It turns out that 0.05 Gcal is used for each cubic meter. However, to compensate for heat loss, this coefficient is overestimated to 0.059 Gcal.
Conversion of Gcal to kW / hour
Thermal energy can be measured in various units, but in the official documentation from housing and communal services it is calculated in Gcal. Therefore, it is worth knowing how to convert other units to gigacalories.
The easiest way to do this is when the ratio of these quantities is known. For example, consider the watts (W), which measures the power output of most boilers or heaters.
Before considering the conversion of Gcal to this value, it is worth remembering that, like a calorie, a watt is small. Therefore, more often use kW (1 kilowatt, is equal to 1000 watts) or mW (1 megawatt equals 1000,000 watts).
In addition, it is important to remember that power is measured in W (kW, mW), but they are used to calculate the amount of consumed / produced electricity.In this regard, it is not the conversion of gigacalories to kilowatts that is considered, but the conversion of Gcal to kW / h.
How can this be done? In order not to suffer with the formulas, it is worth remembering the "magic" number 1163. That is how many kilowatts of energy you need to spend in an hour to get one gigacalorie. In practice, when converting from one unit of measurement to another, it is simply necessary to multiply the amount of Gcal by 1163.
For example, let's convert 0.05 Gcal in kWh / hour required to heat one cubic meter of water by 50 ° C. It turns out: 0.05 x 1163 \u003d 58.15 kW / hour. These calculations are especially helpful for those who are thinking about changing. gas heating for a more environmentally friendly and economical electric.
If we are talking about huge volumes, it is possible to translate not into kilowatts, but into megawatts. In this case, you need to multiply not by 1163, but by 1.163, since 1 mW \u003d 1000 kW. Or simply divide the result in kilowatts by a thousand.
Transfer to Gcal
Sometimes it is necessary to carry out the reverse process, that is, to calculate how many Gcal is contained in one kW / hour.
When converting to gigacalories, the number of kilowatt-hours must be multiplied by another "magic" number - 0.00086.
The correctness of this can be verified by taking the data from the previous example.
So, it was calculated that 0.05 Gcal \u003d 58.15 kW / h. Now it's worth taking this result and multiplying it by 0.00086: 58.15 x 0.00086 \u003d 0.050009. Despite the slight difference, it almost completely coincides with the original data.
As in previous calculations, it is necessary to take into account the fact that when working with especially large volumes of substances, it will be necessary to convert not kilowatts, but megawatts to gigacalories.
How is this done? In this case, again, you need to take into account that 1 mW \u003d 1000 kW. Based on this, in the "magic" number, the comma is moved by three zeros, and voila, 0.86 is obtained. It is on him that you need to multiply in order to make a transfer.
By the way, a slight discrepancy in the answers is due to the fact that the coefficient 0.86 is a rounded version of the number 0.859845. Of course, for more accurate calculations, you should use it. However, if we are talking only about the amount of energy used to heat an apartment or house, it is better to simplify.
All summer red gossips in soft moors sang and danced, and now, when the cold comes, you have to take pencils in your hands. After all, "heating, as there was no, and no". And it is necessary to present at least some arguments of the heating network, calculating the heat received from it, for which it was, after all, "sealed".
When you need to dot the "i"
But a quite reasonable question arises: "How to count what is invisible and capable of disappearing in an instant, literally through the window." You shouldn't despair of this struggle with air, it turns out that there are quite intelligible mathematical calculations of the calories received for heating.
Moreover, all these calculations are hidden in the official documents of public utilities. As usual in these institutions, there are several such documents, but the main one is the so-called "Rules for accounting for heat energy and heat carrier". It is he who will help to solve the question - how to calculate Gcal for heating.
Actually, the problem can be solved quite simply and no calculations will be needed if you have a meter of not just water, but hot water. The readings of such a meter are already "crammed" with data on the received heat. By taking readings, you multiply it by the cost rate and get the result.
Basic formula
The situation becomes more complicated if you do not have such a counter. Then you have to be guided by the following formula:
Q \u003d V * (T1 - T2) / 1000
In the formula:
- Q is the amount of heat energy;
- V is the volume of hot water consumption in cubic meters or tons;
- T1 is the hot water temperature in degrees Celsius. More precisely, in the formula, use the temperature, but reduced to the corresponding pressure, the so-called "enthalgy". But in the absence of a better - appropriate sensor, we simply use the temperature, which is close to enthalgy. Professional heat metering units are able to calculate exactly the enthalgy. Often this temperature is not available for measurement, therefore, they are guided by the constant "from ZhEKA", which can be different, but usually is 60-65 degrees;
- T2 - temperature cold water in degrees Celsius. This temperature is taken in the cold water pipe of the heating system. As a rule, consumers do not have access to this pipeline, therefore it is customary to take constant recommended values \u200b\u200bdepending on heating season: in season - 5 degrees; out of season - 15;
- The coefficient “1000” allows you to get rid of 10-digit numbers and get the data in gigacalories (not just in calories).
As follows from the formula, it is more convenient to use a closed heating system, into which the required volume of water is poured once and in the future it does not flow. But in this case, you are prohibited from using hot water from the system.
Using closed system forces us to slightly improve the above formula, which already takes the form:
Q \u003d ((V1 * (T1 - T)) - (V2 * (T2 - T))) / 1000
- V1 is the flow rate of the coolant in the supply pipeline, regardless of whether the coolant is water or steam;
- V2 is the flow rate of the coolant in the return pipeline;
- T1 is the temperature of the coolant at the inlet, in the supply pipeline;
- T2 is the temperature of the coolant at the outlet, in the return pipeline;
- T is the cold water temperature.
Thus, the formula consists of the difference of two factors - the first gives the value of the incoming heat in calories, the second - the value of the output heat.
Useful advice! As you can see, there is not much mathematics, but calculations still have to be done. Of course, you can immediately rush to your calculator on your mobile phone. But he advises you to create simple formulas in one of the most famous computer office programs - the so-called spreadsheet processor Microsoft Excel included in the Microsoft Office suite. In Excel, you can not only quickly calculate everything, but also play with the initial data, simulate various situations. Moreover, Excel will help you with the construction of graphs for the receipt - consumption of heat, and this is a "non-kill" map in a future possible conversation with government agencies.
Alternative options
How exist different ways providing housing with heat by choosing a heat carrier - water or steam, so there are alternative methods for calculating the heat received. Here are two more formulas:
- Q \u003d ((V1 * (T1 - T2)) + (V1 - V2) * (T2 - T)) / 1000
- Q \u003d ((V2 * (T1 - T2)) + (V1 - V2) * (T1 - T)) / 1000
Thus, calculations can be done with your own hands, but it is important to coordinate your actions with the calculations of heat supplying organizations. Their calculation instructions may be completely different from yours.
Useful advice! Often reference books provide information not in the national system of units of measurement, to which the calories belong, but in the international system "C". Therefore, we advise you to remember the conversion factor of kilocalories to kilowatts. It is equal to 850. In other words, 1 kilowatt is equal to 850 kilocalories. From here it is no longer difficult to translate gigacalories, given that 1 gigacalorie is a million calories.
All counters, and not only the simplest brownies, unfortunately suffer from some measurement error. This is a normal situation, unless, of course, the error exceeds all conceivable limits. To calculate the error (relative, in percent), a special formula is also used:
R \u003d (V1 - V2) / (V1 + V2) * 100,
- V1 and V2 are the previously considered indicators of the coolant flow rate, and
- 100 - conversion factor to percent.
The permissible percentage of error in calculating heat is considered to be no more than 2 percent, given that the error of measuring instruments is no more than 1 percent. You can, of course, do with the old proven method, here you don't really need to do any calculations.
Presentation of the received data
The price of all calculations is your confidence in the adequacy of your own financial costs to the heat received from the state. Although, in the end, you still will not understand what gcal is in heating. In all honesty, let's say that in many ways this is the magnitude of our sense of self and attitude to life. Certainly, you need to have some base "in numbers" in your head. And it is expressed in what is considered a good norm, when for an apartment of 200 square meters your formulas give 3 Gcal per month. Thus, if the heating season lasts 7 months - 21 Gcal.
But all these values \u200b\u200bare quite difficult to imagine "in the shower" when you really need warmth. All these formulas and even the results they give you correctly will not warm you up. They will not explain to you why, even with 4 Gcal per month, you still feel warm. And the neighbor has only 2 gcal, but he does not boast and constantly keeps the window open.
There can be only one answer - his atmosphere is also warmed by the warmth of those around him, and you have no one to cuddle with, although "the room is full of people." He gets up in the morning at 6 and runs in any weather to exercise, and you lie to the last under the covers. Warm yourself from the inside, hang a photo of the family on the wall - everyone in summer swimsuits on the beach in Foros, watch more often the video of the last climb to Ai-Petri - everyone is naked, hot, then you won't even feel a couple of hundred calories outside.
Everyone, at least indirectly, is familiar with such a concept as "calorie". What is it and what is it for? What exactly does it mean? Such questions arise, especially if it is necessary to increase it to kilocalories, megacalories or gigacalories, or convert it to other values, for example, Gcal to kW.
What is a calorie
Calorie is not part of the international metric measurement system, but this concept is widely used to refer to the amount of energy released. It indicates how much energy must be expended to heat 1 g of water so that this volume increases the temperature by 1 ° C under standard conditions.
There are 3 generally accepted designations, each of which is used depending on the area:
- The international calorie value, which equals 4.1868 J (Joule), and is referred to as "calories" in Russian Federation and cal - in the world;
- In thermochemistry - a relative value, approximately equal to 4.1840 J with the Russian designation cal th and the world designation cal th;
- 15-degree calorie index, equal to approximately 4.1855 J, which in Russia is known as "cal 15", and in the world - cal 15.
Initially, calories were used to find the amount of heat released when generating fuel energy. Subsequently, this value began to be used to calculate the amount of energy expended by an athlete when performing any physical activity, since the same physical laws apply for these actions.
Since fuel is needed to generate heat, then, by analogy with heat power in simple life, the body also needs a "refueling" to generate energy - food that people eat regularly.
A person receives a certain amount of calories, depending on which product he consumed.
The more calories a person received in the form of food, the more energy he receives for sports. However, people do not always consume the amount of calories that is necessary to maintain normal body processes and perform physical activity. As a result, some lose weight (with a calorie deficit), while others gain weight.
Calorie content is the amount of energy received by a person as a result of the absorption of a particular product
On the basis of this theory, many principles of diets and rules of healthy eating are built. The optimal amount of energy and macronutrients that a person needs per day can be calculated according to the formulas of renowned nutritionists (Harris-Benedict, Mifflin-Saint Geor), using standard parameters:
- Age;
- Growth;
- An example of daily activity;
- Lifestyle.
These data can be used by changing them for yourself - for painless weight loss, it is enough to create a deficit of 15-20% of the daily calorie intake, and for a healthy weight gain - a similar surplus.
What is a Gigacalorie, and how many calories are in it
The concept of Gigacalorie is most often found in documents in the field of thermal power engineering. This value can be found in receipts, notices, payments for heating and hot water.
It means the same as a calorie, but in a larger volume, as evidenced by the prefix "Giga". Gcal determines that the original value was multiplied by 10 9. Speaking simple language: 1 Gigacalorie - 1 billion calories.
Like a calorie, a Gigacalorie does not belong to the metric system of physical quantities.
The table below shows a comparison of values \u200b\u200bfor example:
The need to use Gcal is due to the fact that when heating the volume of water required for heating and household needs of the population, even one residential building releases a colossal amount of energy. Writing numbers that represent it in documents in calorie format is too long and inconvenient.
A value such as a gigacalorie can be found in payment documents for heating
You can imagine how much energy is consumed during the heating season on an industrial scale: when heating 1 block, district, city, country.
Gcal and Gcal / h: what is the difference
If it is necessary to calculate the payment by the consumer for the services of the state heat power industry (heating a house, hot water), a value such as Gcal / h is used. It denotes a time reference - how many Gigacalories are consumed during heating for a given period of time. Sometimes it is also replaced by Gcal / m 3 (how much energy is needed to transfer heat to a cubic meter of water).
Q \u003d V * (T1 - T2) / 1000, where
- V is the volume of liquid consumption in cubic meters / tons;
- T1 is the temperature of the incoming hot liquid, which is measured in degrees Celsius;
- T2 is the temperature of the supplied cold liquid by analogy with the previous indicator;
- 1000 is an auxiliary coefficient that simplifies the calculations, eliminating the numbers in the tenth digit (automatically converts kcal to Gcal).
This formula is often used to build the principle of operation of heat meters in private apartments, houses or businesses. This measure is necessary in case of a sharp increase in the cost of this utility service, especially when the calculations are generalized based on the area / volume of the room that is heated.
If the system is installed in the room closed type (hot liquid is poured into it once without additional water intake), the formula is modified:
Q \u003d ((V1 * (T1 - T2)) - (V2 * (T2 - T))) / 1000, where
- Q is the amount of heat energy;
- V1 is the volume of the consumable thermal substance (water / gas) in the pipeline through which it enters the system;
- V2 is the volume of thermal substance in the pipeline through which it returns back;
- T1 is the temperature in degrees Celsius in the pipeline at the inlet;
- T2 - temperature in degrees Aim in the pipeline at the outlet;
- T is the cold water temperature;
- 1000 - auxiliary coefficient.
This formula is based on the difference between the inlet and outlet values \u200b\u200bof the heating medium in the room.
Depending on the use of one or another energy source, as well as the type of thermal substance (water, gas), alternative calculation formulas are also used:
- Q \u003d ((V1 * (T1 - T2)) + (V1 - V2) * (T2 - T)) / 1000
- Q \u003d ((V2 * (T1 - T2)) + (V1 - V2) * (T1 - T)) / 1000
In addition, the formula changes when electrical devices are included in the system (eg underfloor heating).
How Gcal are calculated for hot water and heating
Heating is calculated using formulas similar to the formulas for finding the value of Gcal / h.
An approximate formula for calculating payment for warm water in residential premises:
P i gv \u003d V i gv * T x gv + (V v cr * V i gv / ∑ V i gv * T v cr)
Used quantities:
- P i gv - the required value;
- V i gw - the volume of hot water consumption for a certain time period;
- T x gv - the established tariff payment for hot water supply;
- V v gv - the volume of energy expended by the company that is engaged in heating and supplying it to residential / non-residential premises;
- ∑ V i gv - the sum of the consumption of warm water in all rooms of the house, in which the calculation is made;
- T v gv - tariff payment for thermal energy.
This formula does not take into account the indicator of atmospheric pressure, since it does not significantly affect the final sought value.
The formula is approximate and is not suitable for self-calculation without prior consultation. Before using it, you need to contact your local utilities for clarification and adjustment - perhaps they use different parameters and formulas for calculation.
Calculation of the amount of payment for heating is very important, since often impressive amounts are not justified
The calculation result depends not only on the relative temperature values \u200b\u200b- it is directly influenced by the tariffs set by the government for the consumption of hot water supply and space heating.
The computational process is greatly simplified if you install a heating meter for an apartment, entrance or residential building.
It should be borne in mind that even the most accurate counters can tolerate errors in their calculations. It can also be determined by the formula:
E \u003d 100 * ((V1 - V2) / (V1 + V2))
The presented formula uses the following indicators:
- E - error;
- V1 - the volume of consumed hot water supply upon admission;
- V2 - consumed hot water at the outlet;
- 100 is an auxiliary coefficient that converts the result to a percentage.
According to the requirements, average value the error of the calculating device is about 1%, and the maximum allowable is 2%.
Video: example of calculating heating bills
How to convert Gcal to kWh and Gcal / h to kW
On the different devices thermal power spheres indicate different metric values. So, on heating boilers and heaters more often indicate kilowatts and kilowatts per hour. Gcal are more common on calculating devices (meters). The difference in magnitude interferes correct calculation the required value by the formula.
To facilitate the calculation process, it is necessary to learn how to convert one value to another and vice versa. Since the quantities have constant value, then it is not difficult - 1 Gcal / h is equal to 1162.7907 kW.
If the value is presented in megawatts, it can be converted back to Gcal / h by multiplying by a constant value of 0.85984.
Below are auxiliary tables that allow you to quickly convert values \u200b\u200bfrom one to another:
The use of these tables will greatly simplify the process of calculating the cost of heat energy. In addition, to simplify actions, you can use one of the online converters offered on the Internet that convert physical quantities one into the other.
Self-calculation of the consumed energy in Gigacalories will allow the owner of residential / non-residential premises to control the cost of utilities, as well as the work of utilities. With the help of simple calculations, it becomes possible to compare the results with those in the received payment receipts and contact the appropriate authorities in case of a difference in indicators.
CONSIDERING THERMAL ENERGY!
When you start to understand the issue of calculating heat energy, it seems so difficult, you assume that only an academician can figure out these calculations, and then with a specialization in housing and communal services (probably, there are no such things). But when you get overgrown with terms and get used to the essence of this question, everything becomes clear and becomes not so scary.
There is an opinion that in the post-Soviet space we, as always, differ from the entire planet, and instead of counting thermal energy in joules (J), we count it in long-standing non-systemic units of calories, or rather in calorie-derived units of thermal energy - gigacalories ( Gcal). It's essentially the same thing, only with the extra nine zeros (109 calories).
Due to the fact that in different industries different temperatures are taken as the reference water temperature, there are several different definitions of calories in joules (J).
1 calm \u003d 4.1868 J (1 J ≈ 0.2388459 calm) International calorie, 1956.
1 calt \u003d 4.184 J (1 J \u003d 0.23901 calt) Thermochemical calorie.
1 cal15 \u003d 4.18580 J (1 J \u003d 0.23890 cal15) Calorie at 15 ° C.
The unit of measurement Joule (J) is the unit of energy in the СІ system.
It is defined as the work of a force of one Newton at a distance of 1 meter, from this it follows that 1 J \u003d 1 N * m \u003d 1 kg * m ** 2 / sec ** 2. In turn, this is associated with the definition of the unit of mass in kilograms (kg), length in meters (m) and time in seconds (sec) in the СІ system.
One J \u003d 0.239 calories, one GJ \u003d 0.239 Gcal, and one gigacalorie \u003d 4.186 GJ.
Today, as is known to a greater extent, the beautiful half of humanity, it is customary to measure the energy value (caloric content) of food in calories - Kcal. The whole world has long forgotten about the use of Gcal for assessment in heat and power engineering, heating systems, utilities, and we persistently continue to count in this way.
But be that as it may, from here comes another derived unit of measurement Gcal / hour (gigacalorie per hour). It also characterizes the amount of heat energy used or produced by this or that equipment or heat carrier in one hour. Gcal / hour as a value is equivalent to thermal power, but we do not need it yet.
For a better understanding of the issue, let's look a little more at some units of measurement and do some simple arithmetic calculations.
Once again, so, to consolidate understanding. One Calorie equals 1 calorie, one Kilocalorie equals 1000 calories, one Mega calorie equals 1,000,000 calories, one Gigacalorie equals 1,000,000,000 (1 × 109 calories)
One calorie gives off the amount of heat that is needed to heat one gram of water by one degree Celsius at a pressure of one atmosphere (we will also lower the pressure for now, although this is the same value of all formulas and its standard value of atmospheric pressure is 101.325 kPa).
Now we can assume that one Gigacalorie square meter the total area of \u200b\u200bthe room is the amount of heat energy consumption for heating the room. And as a confirmation of what was said, this unit of measurement was provided in the "Rules for the provision of utilities for use in calculations."
In other words, one gigacalorie (Gcal) heats one thousand cubic meters of water per one degree Celsius, or about 16.7 cubic meters of water at 60 degrees Celsius (1000/60 \u003d 16.666667).
This information can be useful when evaluating the performance of hot water meters (DHW).
Heat meters keep their records in the unit of measurement Gcal or, rarely, in megajoules. As is known, power generating companies use Gcal in their calculations.
Each fuel, during combustion, has its own heat transfer rates for a certain amount of this fuel, the so-called calorific values \u200b\u200bof solid and liquid fuels are measured in Kcal / kg. If you are interested, then look in the net, but as an example, I will say that the calculations use conventional fuel, the calorific value of which is equal to 7 Gcal per 1 ton of fuel, and for natural gas - 8.4 Gcal per 1,000 cubic meters of gas.
If you have mastered all these meanings, we can try to check the energy company or our neighbors, heat terrorists, without leaving the apartment!
How to check everyone without leaving the apartment?
According to the source of this information, if you can carry out all these calculations correctly, then on the basis of your numbers you will be able to check the energy company and make a claim to your operating organization or condominiums, with the requirement for recalculation.
Let's try to do this using the data obtained on the forum at the site address: gro-za.pp.ua/forum/index.php?topic\u003d4436.0
So, a few more numbers for "assimilation":
Kilowatt hour. It is mainly used for payments for electricity (in electricity meters). It comes from the unit of power, which is called Watt (W) and is equal to 1 Joule energy used for 1 second.
For example, electric lamp 60 W power for 1 hour consumes 60 Wg \u003d 0.060 KWg of energy. Or in joules and kilocalories: 1 kWg \u003d 3600 KJ \u003d 860.4 Kilocalories \u003d 0.8604 megacalories; 1 gigacalorie \u003d 1162.25 KWh \u003d 1.16225 MWh (megawatt hours); 1 MWg \u003d 0.8604 Gcal. The unit of power Watt is used in assessing the heat transfer of heating devices (heat radiators).
So how can this information be used to the benefit of the district heating consumer?
For this we need to assimilate some more data. Below is suggested reference Information for heat transfer of two types of radiators.
If your type of radiator is not among these two, you are out of luck, then if you are "lucky" you will find detailed information about your type of radiator in the net or in some reference books.
SO FIRST TYPE OF RADIATOR. Rated heat dissipation aluminum radiator Calidor type Italian by Fondital (according to the EN 442-2 standard) is Q \u003d 194 W at Dt \u003d (Trad-Tpov) \u003d 60 degrees Celsius, where Trad - average temperature water in the radiator, Тпов - air temperature in the room. Trad is equal to the difference in water temperature at the inlet and outlet of the radiator. With a single-pipe coolant supply, this difference is practically equal to the inlet temperature. For other values, Dt is the value of heat transfer, which is taken from the correction factor K \u003d ((Dt / 60)) ^ n, de ^ is the exponentiation operation, n \u003d 1.35.
Example: radiator temperature 45 degrees, air temperature 20 degrees. Then K \u003d ((45-20) / 60) ^ 1.35 \u003d 0.3067, and Q \u003d 194 x 0.3067 \u003d 59.5 W - three times less than the nominal!
SECOND TYPE OF RADIATOR. The most common heating radiator is cast iron MS-140M4 500-0.9. The reference books indicate the power of thermal radiation for cast iron section MS-140 in the amount of 160-180 W at a coolant temperature of 90 ° C. But, this heat transfer is achievable only under ideal (laboratory) conditions, which in real life unattainable. Because the radiation power significantly depends on temperature, therefore, the real heat transfer of the cast-iron section at 60 ° C will be no more than 80 W, and at 45 ° C - about 40 W. The flow of heated water from the indoor system to cast iron battery happens randomly. In order for the average temperature of the entire radiator to be 60 ° C, it is necessary to provide water supply with at least 75 ° C, then water with a temperature of about 45 ° C will go to the “return”. Calculate how powerful the heat exchanger must be to heat a ton of water to a temperature of 75 ° C. It is necessary to take into account that ten degrees is spent in thick metal pipesthat are brought to the house. Therefore, the elevator unit (heat exchanger) must give 85 ... 90 ° C and work to the edge. Provide temperature cast iron radiator 90 ° C hot water (non-steam) heating systems is impossible and unsafe - you can get burns even at 70 ° C.
In addition, it should be noted that the curtains on the radiator lead to a decrease in heat transfer by 10-18%, the area of \u200b\u200bthe cast-iron radiator, the coating oil paint gives a decrease in heat transfer by 13%, and coating with zinc white increases heat transfer by 2.5%.
Having data on the actual temperature of the coolant at the inputs of apartment heating radiators, data on the heat transfer (in watts) of one section of the heat radiator at the nominal temperature, you calculate the actual heat transfer at the actual temperature of the coolant. Multiply the data obtained by the number of seconds of time during which the results of measurements / calculations took place. Obtain the amount of heat energy in Joules. You do the conversion in gigacalories.
After that, you conclude who owes whom and how much. If you have to, file a claim with the balance holder of the house with a requirement for a recount.
EXAMPLE:
Let one section of the central heating radiator actually give out 30 watts. Let the area of \u200b\u200bthe apartment be 84 sq.m. According to the above recommendation, you should have 1 section per 1 square meter, that is, you need 84 sections, or 6 radiators, 14 sections each. The power of one radiator is 30x14 \u003d 420 W \u003d 0.42 KW. For a day, one radiator will give 0.42x24 \u003d 10.08 KWg of heat energy, and 6 radiators - respectively 10.08x6 \u003d 60.48 KWg. For a month we will receive 60.48x30 \u003d 1814.4 kWh. We translate into gigacalories: (1814.4 / 1000) \u003d 1.8144 MWtg. x 0.8604 \u003d 1.56 Gcal. The heated season lasts 6 months, of which more or less full heating need within 5 months, because in the first half of April the weather is already warm. And the second half of October is also free of frost. Thus, with the marked parameters, you will get 1.56 x 5 \u003d 7.8 Gcal. instead of the normative 0.147 Gcal / m2 x 84 m2 \u003d 12.348 Gcal. That is, you received only 100% x 7.8 / 12.348 \u003d 63% of the standard volume of heat energy, and 37% are the extra funds accrued for the DH.
I hope everyone understands everything, but if it is not clear, then I am not to blame!
Anyway, I think that we are already ready for the main section of our conversation.
Let's start with the concepts of "work" and "power". Work is part of the internal energy expended by a person or a machine over a period of time. In the process of such work, a person or a machine warms up, generating heat. Therefore, both internal energy and the amount of released or absorbed heat, as well as work, are measured in the same units - joules (J), kilojoules (kJ) or megajoules (MJ).
The faster work is done or heat is released, the more intensively internal energy is consumed. By a measure of this intensity is the power, measured in watts (W), kilowatts (kW), megawatts (MW), and gigawatts (GW). Power is the work done per unit of time (whether it be engine work or work electric current). Thermal power is the amount of heat transferred per unit of time to the coolant (water, oil) from the combustion of fuel (gas, fuel oil) in the boiler.
Calorie was introduced back in 1772 Swedish experimental physicist Johann Wilcke as a unit of measurement for heat. Currently, a unit multiple of a calorie, a gigacalorie (Gcal), is actively used in such spheres of life as utilities, heating systems and heat power engineering. Its derivative is also used - gigacalorie per hour (Gcal / h), which characterizes the rate of heat release or heat absorption by one or another equipment. Now let's try to calculate what one calorie is equal to.
Back in school, in physics lessons, we were taught that in order to heat any substance, it must be given a certain amount of heat. There was even such a formula Q \u003d c * m * ∆t, where Q means an unknown amount of heat, m is the mass of the heated substance, c is the specific heat of this substance, and ∆t is the temperature difference by which the substance is heated. So, a calorie is called an off-system unit of the amount of heat, defined as "the amount of heat spent on heating 1 gram of water per 1 degree Celsius at atmospheric pressure of 101325 Pa."
Since heat is measured in joules, then using the above formula, we find out what is 1 calorie (cal) in joules... To do this, we take from the physics reference book the value of the specific heat capacity of water under normal conditions ( atmosphere pressure p \u003d 101325 Pa, temperature t \u003d 20 ° C): c \u003d 4183 J / (kg * ° C). Then one calorie will be equal to:
- 1 cal \u003d 4183 [J / (kg * ° C)] * 0.001 kg * 1 ° C \u003d 4.183 J.
However, the calorie value depends on the heating temperature, so its value is not constant. For practical purposes, the so-called international calorie or simply calorie is used, which is 4.1868 J.
Memo 1
- 1 cal \u003d 4.1868 J, 1 kcal \u003d 1000 cal, 1 Gcal \u003d 1 billion cal \u003d 4186800000 J \u003d 4186.8 MJ;
- 1 J \u003d 0.2388 cal, 1 MJ \u003d 1 million J \u003d 238845.8966 cal \u003d 238.8459 kcal;
- 1 Gcal / h \u003d 277777.7778 cal / s \u003d 277.7778 kcal / s \u003d 1163000 J / s \u003d 1.163 MJ / s.
Gigacalories or kilowatts
Let us finally figure out what is the difference between these units of measurement. Suppose we have a heating device, for example, a kettle. Take 1 liter of cold tap water (temperature t1 \u003d 15 ° C) and boil it (heat it to t2 \u003d 100 ° C). Electric power kettle - P \u003d 1.5 kW. How much heat will the water absorb? To find out, we apply the familiar formula, while taking into account that the mass of 1 liter of water m \u003d 1 kg: Q \u003d 4183 [J / (kg * ° C)] * 1 kg * (100 ° C-15 ° C) \u003d 355555 J \u003d 84922.8528 cal≈85 kcal.
How long does it take for a kettle to boil? Let all the energy of the electric current go to heating the water. Then unknown time we will find, using the energy balance: "The energy consumed by the kettle is equal to the energy absorbed by the water (excluding losses)." The energy consumed by the kettle during the time τ is equal to P * τ. The energy absorbed by water is equal to Q. Then, based on the balance, we obtain P * τ \u003d Q. Hence, the heating time of the kettle will be: τ \u003d Q / P \u003d 355555 J / 1500 W ≈ 237 s ≈ 4 minutes. The amount of heat transferred by the kettle to the water per unit of time is its thermal power. In our case, it will amount to Q / τ \u003d 84922.8528 cal / 237 s≈358 cal / s \u003d 0.0012888 Gcal / h.
Thus, kW and Gcal / h are units of power, and Gcal and MJ are units of heat and energy. How can such calculations be applied in practice? If we receive a receipt for payment for heating, then we pay for the heat that the supplying organization supplies us through pipes. This heat is taken into account in gigacalories, that is, in the amount of heat consumed by us during the calculation period. Do I need to convert this unit to joules? Of course not, because we're just paying for a specific number of gigacalories.
However, it is often necessary to choose one or another for a house or apartment. heating devicese.g. air conditioner, radiator, boiler or gas boiler. In this connection, you need to know in advance heat outputrequired to heat the room. Knowing this power, you can select the appropriate device. It can be specified both in kW and in Gcal / h, as well as in BTU / h units (British Thermal Unit - British Thermal Unit, h - hour). The following guide will help you convert kW to Gcal / h, kW to BTU / h, Gcal to kWh, and BTU to kWh.
Memo 2
- one W \u003d one J / s \u003d 0.2388459 cal / s \u003d 859.8452 cal / h \u003d 0.8598 kcal / h;
- one kW \u003d one kJ / s \u003d 1000 J / s \u003d 238.8459 cal / s \u003d 859845.2279 cal / h \u003d 0.00085984523 Gcal / h;
- one MW \u003d one MJ / s \u003d one million J / s \u003d 1000 kW \u003d 238845.8966 cal / s \u003d 0.85984523 Gcal / h;
- one Gcal / h \u003d one billion cal / h \u003d 1163000 W \u003d 1163 kW \u003d 1.163 MW \u003d 3968156 BTU / h;
- one BTU / h \u003d 0.2931 W \u003d 0.0700017 cal / s \u003d 252.0062 cal / h \u003d 0.2520062 kcal / h;
- one W \u003d 3.412 BTU / h, one kW \u003d 3412 BTU / h, one MW \u003d 3412000 BTU / h.
How is BTU / h defined and what is it used for? 1 BTU is the amount of heatrequired to heat 1 pound of water 1 ° Fahrenheit (° F). This unit is mainly used to indicate the heat output of installations such as air conditioners.
Calculation examples
So we come to the most important thing. How to convert one value to another using the above ratios? It's not all that difficult. Let's look at some examples.
Example 1
The thermal power of the boiler is 30 kW. What is it equal to equivalent powerexpressed in Gcal / h?
Decision. Since 1 kW \u003d 0.00085984523 Gcal / h, then 30 kW \u003d 30 * 0.00085984523 Gcal / h \u003d 0.0257953569 Gcal / h.
Example 2
It is estimated that an air conditioner with a capacity of at least 2.5 kW is required to cool an office. An air conditioner with a capacity of 8000 BTU / h was chosen for the purchase. Is there enough air conditioner capacity to cool the office?
Decision. Since 1 BTU / h \u003d 0.2931 W, then 8000 BTU / h \u003d 2344.8 W \u003d 2.3448 kW. This value is less than the calculated 2.5 kW, therefore the selected air conditioner is not suitable for installation.
Example 3
The heat supplying organization supplied 0.9 Gcal of heat per month. How much power does a radiator need to install so that it produces the same amount of heat per month?
Decision. Suppose that heat was supplied to the house evenly during one month (30 days), therefore, the heat output supplied by the boiler house can be found by dividing the total amount of heat by the number of hours in a month: P \u003d 0.9 Gcal / (30 * 24 h) \u003d 0.00125 Gcal / h. This power in terms of kilowatts will be equal to P \u003d 1163 kW * 0.00125 \u003d 1.45375 kW.
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