Most of all, in the frosty winter months, all people wait for the New Year, and least of all - receipts for heating. Especially their residents do not like apartment buildings, which themselves do not have the ability to control the amount of incoming heat, and often the bills for it are 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 like to calculate gigacalories and convert to other units.
What is called a calorie?
Supporters of a healthy diet or those who are closely monitoring their weight are familiar with the concept of calories. This word means the amount of energy received as a result of processing by the body of eaten food that must be used, otherwise the person will begin to recover.
Paradoxically, the same value is used to measure the amount of thermal energy used to heat the premises.
In physics, it is generally accepted that one calorie is the amount of energy that is needed to heat one gram of H 2 O per 1 ° C at standard atmospheric pressure (101 325 Pa).
By way of abbreviation, this value is referred to as “feces,” or in English cal.
In the metric measurement system, the equivalent of calories is the joule. So, 1 cal = 4.2 J.
The value of calories for human life
In addition to developing various diets for weight loss, this unit is used to measure energy, work and warmth. In this regard, such concepts as "calorie content" are common - that is, the heat of combustible fuel.
In most developed countries, when calculating heating, people do not pay for the amount of cubic meters of gas consumed (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 diluting the substance used with other, cheaper and less high-calorie compounds.
Gigacalorie - what is it and how many calories are there?
As is clear from the definition, the size of 1 calorie is small. For this reason, it is not used to calculate large quantities, especially in the energy sector. Instead, it uses such a thing as gigacaloria. This value is equal to 10 9 calories, and it is recorded in the form of the 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 contains 1000 cal. Thus, we can assume that one gigacalorie is a million kilocalories.
It should be borne in mind that sometimes calories are simply recorded as “feces”. Because of this, confusion arises, and in some sources it is indicated that in 1 Gcal - 1 000 000 cal, although in reality we are talking about 1 000 000 Kcal.
Hekakaloriya and gigakaloriya
In the energy sector, in most cases, Gcal is used as a unit of measurement, but it is often confused with the concept of “hecaloria” (it is hectocalorie).
In this regard, the abbreviation "Gcal" is interpreted by some people as "hecalorie" or "hectocalorie". However, this is wrong. In fact, the aforementioned units of measurement do not exist, and their use in speech is the result of illiteracy, and nothing more.
Gigacalorie and gigacalorie / hour: what is the difference
In addition to the fictitious value in question, such reductions as “Gcal / hour” are sometimes found in receipts. What does it mean and how is it different from ordinary gigacalorie?
This unit of measure shows how much energy was used in one hour.
While just gigacalorie is a measure of the heat consumed over an indefinite period of time. It depends only on the consumer what time frames will be indicated in this category.
Reduction of Gcal / m 3 is much less common . It means how many gigacalories must be used to heat one cubic meter of substance.
Gigacalorie Formula
Having considered the definition of the studied quantity, it is worth finally to find out how to calculate how many gigacalories are used to heat the room in the heating season.
For especially lazy people, there are many online resources on the Internet where specially programmed calculators are presented. It is enough to enter their numerical data into them - and they themselves will calculate the number of consumed gigacalories.
However, it would be nice to be able to do it yourself. To do this, there are several options for the formula. The most simple and understandable among them is the following:
Thermal energy (Gcal / h) = (M 1 x (T 1 -T hv )) - (M 2 x (T 2 -T hv )) / 1000, where:
- M 1 - the mass of heat transferring substance that is supplied through the pipeline. Measured in tons.
- M 2 - the mass of heat transferring substance returning through the pipeline.
- T 1 - the temperature of the coolant in the supply pipe, measured in Celsius.
- T 2 - the temperature of the coolant in returning back.
- T hv - temperature of a cold source (water). It is usually equal to five degrees Celsius, since this is exactly the minimum temperature of the water in the pipeline.
Why housing and utilities when calculating for heating overestimate the amount of energy spent
Carrying out your own calculations, it is worth paying attention that the housing and utilities sector slightly overestimate the standards for the consumption of thermal energy. 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. Such a "premium" is due to the fact that during the transport of hot liquid through the pipeline in the cold season, it tends to cool, that is, inevitable heat loss occurs.
In numbers, it looks as follows. According to the regulations, the temperature of the water in the heating pipes must be at least +55 ° C. And if we take into account that the minimum water t 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, in order to compensate for heat loss, this coefficient is overestimated to 0.059 Gcal.
Conversion of Gcal in kW / h
Thermal energy can be measured in various units, but in the official documentation from the 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, it is worth considering watts (W), which measure the power output of most boilers or heaters.
Before considering the conversion to this Gcal value, it is worth remembering that, like calories, a watt is small. Therefore, they often use kW (1 kilowatt, equal to 1000 watts) or MW (1 megawatt equals 1,000,000 watts).
In addition, it is important to remember that power is measured in watts (kW, mW), but kW / h (kilowatt hours) is used to calculate the amount of electricity consumed / produced . In this regard, it is not considered the conversion of gigacalories to kilowatts, but the conversion of Gcal to kW / h.
How to do this? In order not to be tormented with the formulas, it is worth remembering the “magic” number 1163. That is how many kilowatts of energy you need to spend per hour to get one gigacalorie. In practice, when converting from one unit of measurement to another, it is simply necessary to multiply the number of Gcal by 1163.
For example, let's convert in kW / h the 0.05 Gcal needed to heat one cubic meter of water at 50 ° C. It turns out: 0.05 x 1163 = 58.15 kW / h. These calculations will especially help those who are thinking about changing gas heating to a more environmentally friendly and economical electric.
If we are talking about huge volumes, it can be converted not into kilowatts, but into megawatts. In this case, you need to multiply not by 1163, but by 1.163, since 1 mW = 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, calculate how many Gcal is contained in one kW / hour.
When converted to gigacalories, the number of kilowatt-hours must be multiplied by another “magic” number - 0.00086.
You can check the correctness of this if you take the data from the previous example.
So, it was calculated that 0.05 Gcal = 58.15 kW / h. Now it’s worth taking this result and multiplying it by 0.00086: 58.15 x 0.00086 = 0.050009. Despite a slight difference, it almost completely coincides with the source 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 we need to take into account that 1 mW = 1000 kW. Based on this, in the "magic" number, the comma moves by three zeros, and voila, it turns out 0.86. It is precisely on it that one must multiply in order to make the transfer.
By the way, a small inconsistency 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 it is worth using it. However, if we are talking only about the amount of energy used to heat an apartment or a house, it is better to simplify it.