What is Gcal? Gcal is a gigacalorie, that is, a measuring unit in which thermal energy is calculated. You can calculate Gcal on your own, but having previously studied some information about thermal energy. Consider in the article general information about the calculations, as well as the formula for calculating Gcal.

What is Gcal?

A calorie is a certain amount of energy required to heat 1 gram of water to 1 degree. This condition is met under atmospheric pressure conditions. For calculations of thermal energy, a large value is used - Gcal. A gigacalorie corresponds to 1 billion calories. This value has been used since 1995 in accordance with the document of the Ministry of Fuel and Energy.

In Russia, the average value of consumption per 1 sq.m. is 0.9342 Gcal per month. In each region, this value may vary up or down depending on weather conditions.

What is a gigacalorie if it is converted into ordinary values?

1 Gigacalorie equals 1162.2 kilowatt-hours.
In order to heat 1 thousand tons of water to a temperature of +1 degree, 1 gigacalorie is required.

Gcal in apartment buildings

In apartment buildings, gigacalories are used in thermal calculations. If you know the exact amount of heat that remains in the house, then you can calculate the bill for paying for heating. For example, if a house-wide or individual heating device is not installed in the house, then you will have to pay for centralized heating based on the area of \u200b\u200bthe heated room. In the event that a heat meter is installed, then the wiring is of the horizontal type, either serial or collector. In this embodiment, two risers are made in the apartment for the supply and return pipes, and the system inside the apartment is determined by the residents. Such schemes are used in new homes. That is why residents can independently regulate the consumption of thermal energy, making a choice between comfort and economy.

Adjustment is made as follows:

Due to the throttling of heating batteries, the patency of the heating device is limited, therefore, the temperature in it decreases, and the consumption of thermal energy decreases.
Installation of a common thermostat on the return pipe. In this embodiment, the flow rate of the working fluid is determined by the temperature in the apartment, and if it increases, then the flow rate decreases, and if it decreases, then the flow rate increases.

Gcal in private houses

If we talk about Gcal in a private house, then residents are primarily interested in the cost of heat energy for each type of fuel. Therefore, consider some prices for 1 Gcal for various types of fuel:

- 3300 rubles;
Liquefied gas - 520 rubles;
Coal - 550 rubles;
Pellets - 1800 rubles;
Diesel fuel - 3270 rubles;
Electricity - 4300 rubles.

The price may vary depending on the region, and it is also worth considering that the cost of fuel increases periodically.

General information about Gcal calculations

To calculate Gcal, it is necessary to make special calculations, the procedure for which is established by special regulations. The calculation is carried out by utilities, which can explain to you the procedure for calculating Gcal, as well as decipher any incomprehensible points.

If you have an individual device installed, you will be able to avoid any problems and overpayments. It is enough for you to monthly take readings from the counter and multiply the resulting number by the tariff. The amount received must be paid for the use of heating.

Heat meters

The temperature of the liquid at the inlet and outlet of a certain section of the pipeline.
The flow rate of fluid that moves through heating devices.

Consumption can be determined using heat meters. Heat meters can be of two types:

Wing counters. Such devices are used to account for thermal energy, as well as the consumption of hot water. The difference between such meters and cold water metering devices is the material from which the impeller is made. In such devices, it is most resistant to high temperatures. The principle of operation is similar for two devices:

The rotation of the impeller is transmitted to the accounting device;
The impeller begins to rotate due to the movement of the working fluid;
The transfer is made without direct interaction, but with the help of a permanent magnet.

Such devices have a simple design, but their response threshold is low. And also they have reliable protection against distortion of indications. With the help of an anti-magnetic screen, the impeller is prevented from braking by an external magnetic field.

Devices with a recorder of differences. Such meters operate according to Bernoulli's law, which states that the speed of a liquid or gas flow is inversely proportional to its static movement. If the pressure is recorded by two sensors, it is easy to determine the flow in real time. The counter implies electronics in the design device. Almost all models provide information on the flow and temperature of the working fluid, as well as determine the consumption of thermal energy. You can set the operation manually using a PC. You can connect the device to a PC through the port.

Many residents are wondering how to calculate the amount of Gcal for heating in an open heating system, in which selection for hot water is possible. Pressure sensors are installed on the return pipe and the supply pipe at the same time. The difference that will be in the flow rate of the working fluid will show the amount of warm water that was spent for domestic needs.

Formula for calculating Gcal for heating

If you do not have an individual device, then you must use the following formula for calculating heat for heating: Q \u003d V * (T1 - T2) / 1000, where:

Q is the total amount of heat energy.
V is the volume of hot water consumption. It is measured in tons or cubic meters.
T1 is the hot water temperature and is measured in degrees Celsius. In such a calculation, it is better to take into account such a temperature that will be characteristic of a particular working pressure. This indicator is called enthalpy. If there is no necessary sensor, then take the temperature that will be similar to the enthalpy. Usually the average indicator of such a temperature is in the range of 60-65 degrees Celsius.
T2 is the cold water temperature and is measured in degrees Celsius. As you know, getting to a pipeline with cold water is not easy, so these values are determined by constant values. They, in turn, depend on the climatic conditions outside the house. For example, in the cold season, this value can be 5 degrees, and in the warm season, when there is no heating, it can reach 15 degrees.
1000 is the ratio by which you can get the answer in gigacalories. This value will be more accurate than in regular calories.

In a closed heating system, the calculation of gigacalories takes place in a different form. In order to calculate Gcal in a closed heating system, you must use the following formula: Q = ((V1 * (T1 - T)) - (V2 * (T2 - T))) / 1000, where:

Q - the former volume of thermal energy;
V1 is the flow rate parameter of the heat carrier in the supply pipe. The heat source can be steam or plain water.
V2 - volume of water flow in the outlet pipe;
T1 - temperature in the heat carrier supply pipe;
T2 - temperature at the outlet of the pipe;
T - cold water temperature.

The calculation of thermal energy for heating according to this formula depends on two parameters: the first shows the heat that enters the system, and the second is the heat parameter when the heat carrier is removed through the return pipe.

Other methods of calculating Gcal for heating

Q = ((V1 * (T1 - T2)) + (V1 - V2) * (T2 - T)) / 1000.
Q = ((V2 * (T1 - T2)) + (V1 - V2) * (T1 - T)) / 1000.

All values in these formulas are the same as in the previous formula. Based on the above calculations, we can conclude that you can calculate Gcal for heating yourself. But you should seek advice from special companies that are responsible for supplying heat to the house, since their work and calculation system may differ from these formulas and consist of a different set of measures.

If you decide to make the "Warm floor" system in your private house, then the principle of calculating heating will be completely different. The calculation will be much more difficult, since not only the features of the heating circuit should be taken into account, but also the values of the electrical network from which the floor is heated. The companies that are responsible for overseeing underfloor heating installation work will be different.

Many residents have difficulty converting kilocalories to kilowatts. This is due to the many benefits of measuring units in the international system, which is called "Ci". When converting kilocalories to kilowatts, a factor of 850 should be used. That is, 1 kW equals 850 kcal. Such a calculation is much simpler than others, since it is not difficult to find out the required amount of gigacalories. 1 gigacalorie = 1 million calories.

During the calculation, it should be remembered that any modern devices have a small error. For the most part, they are acceptable. But you need to calculate the error yourself. For example, this can be done using the following formula: R = (V1 - V2) / (V1 + V2) * 100, where:

R is the error of a common house heating device.
V1 and V2 are the previously mentioned parameters of the water flow in the system.
100 is a coefficient that is responsible for converting the resulting value into a percentage.
In accordance with operational standards, the maximum error that can be - 2%. In general, this figure does not exceed 1%.

Results of calculations of Gcal for heating

If you correctly calculated the consumption of Gcal of thermal energy, then you can not worry about overpayments for utilities. If you use the above formulas, then we can conclude that when heating a residential building with an area of up to 200 sq.m. you will need to spend about 3 Gcal for 1 month. If we take into account that the heating season in many regions of the country lasts about 6 months, then we can calculate the approximate consumption of thermal energy. To do this, we multiply 3 Gcal by 6 months and get 18 Gcal.

Based on the information indicated above, we can conclude that all calculations on the consumption of thermal energy in a particular house can be done independently without the help of special organizations. But it is worth remembering that all data must be calculated exactly according to special mathematical formulas. In addition, all procedures must be coordinated with special bodies that control such actions. If you are not sure that you can do the calculation yourself, you can use the services of professional specialists who are engaged in such work and have materials available that describe in detail the entire process and photos of samples of the heating system, as well as their connection diagrams.

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1 kilowatt [kW] = 0.239005736137667 kilocalorie (th) per second [kcal(T)/s]

Initial value

Converted value

watt exawatt petawatt terawatt gigawatt megawatt kilowatt hectowatt decawatt deciwatt centiwatt milliwatt microwatt nanowatt picowatt femtowatt attowatt horsepower horsepower metric horsepower boiler horsepower electric horsepower pumping horsepower horsepower (German) int. thermal unit (IT) per hour Brit. thermal unit (IT) per minute Brit. thermal unit (IT) per second Brit. thermal unit (thermochemical) per hour Brit. thermal unit (thermochemical) per minute Brit. thermal unit (thermochemical) per second MBTU (international) per hour Thousand BTU per hour MMBTU (international) per hour Million BTU per hour ton of refrigeration kilocalorie (IT) per hour kilocalorie (IT) per minute kilocalorie (IT) per second kilocalorie (thm) per hour kilocalorie (thm) per minute kilocalorie (thm) per second calorie (thm) per hour calorie (thm) per minute calorie (thm) per second calorie (thm) per hour calorie (thm) per minute calorie (thm) per second ft lbf per hour ft lbf/minute ft lbf/second lb-ft per hour lb-ft per minute lb-ft per second erg per second kilovolt-ampere volt-ampere newton-meter per second joule per second exajoule per second petajoule per second terajoule per second gigajoule per second megajoule per second kilojoule per second hectojoule per second decajoule per second decijoule per second centijoule per second millijoule per second microjoule per second nanojoule per second picojoule per second femtojoule per second attojoule per second joule per hour joule per minute kilojoule per hour kilojoule per minute Planck power

The principle of operation of the Geiger counter

More about power

General information

In physics, power is the ratio of work to the time during which it is performed. Mechanical work is a quantitative characteristic of the action of a force F on the body, as a result of which it moves a distance s. Power can also be defined as the rate at which energy is transferred. In other words, power is an indicator of the machine's performance. By measuring the power, you can understand how much and how fast the work is done.

Power units

Power is measured in joules per second, or watts. Along with watts, horsepower is also used. Before the invention of the steam engine, the power of engines was not measured, and, accordingly, there were no generally accepted units of power. When the steam engine began to be used in mines, engineer and inventor James Watt began to improve it. In order to prove that his improvements made the steam engine more productive, he compared its power to the performance of horses, since horses have been used by people for many years, and many could easily imagine how much work a horse can do in a certain amount of time. In addition, not all mines used steam engines. On those where they were used, Watt compared the power of the old and new models of the steam engine with the power of one horse, that is, with one horsepower. Watt determined this value experimentally, observing the work of draft horses at the mill. According to his measurements, one horsepower is 746 watts. Now it is believed that this figure is exaggerated, and the horse cannot work in this mode for a long time, but they did not change the unit. Power can be used as a measure of productivity, as increasing power increases the amount of work done per unit of time. Many people realized that it was convenient to have a standardized unit of power, so horsepower became very popular. It began to be used in measuring the power of other devices, especially vehicles. Even though watts have been around for almost as long as horsepower, horsepower is more commonly used in the automotive industry, and it's clearer to many buyers when a car's engine power is listed in those units.

Power of household electrical appliances

Household electrical appliances usually have a power rating. Some lamps limit the power of the bulbs that can be used in them, for example, no more than 60 watts. This is because higher wattage bulbs generate a lot of heat and the bulb holder can be damaged. And the lamp itself at a high temperature in the lamp will not last long. This is mainly a problem with incandescent lamps. LED, fluorescent and other lamps generally operate at lower wattage for the same brightness and if used in luminaires designed for incandescent lamps there are no wattage problems.

The greater the power of the electrical appliance, the higher the energy consumption and the cost of using the appliance. Therefore, manufacturers are constantly improving electrical appliances and lamps. The luminous flux of lamps, measured in lumens, depends on the power, but also on the type of lamps. The greater the luminous flux of the lamp, the brighter its light looks. For people, it is high brightness that is important, and not the power consumed by the llama, so recently alternatives to incandescent lamps have become increasingly popular. Below are examples of types of lamps, their power and the luminous flux they create.

450 lumens:

Incandescent lamp: 40 watts
Compact fluorescent lamp: 9-13 watts
LED lamp: 4-9 watts

800 lumens:

Incandescent lamp: 60 watts
Compact fluorescent lamp: 13-15 watts
LED lamp: 10-15 watts

1600 lumens:

Incandescent lamp: 100 watts
Compact fluorescent lamp: 23-30 watts
LED lamp: 16-20 watts

From these examples, it is obvious that with the same luminous flux created, LED lamps consume the least electricity and are more economical than incandescent lamps. At the time of this writing (2013), the price of LED lamps is many times higher than the price of incandescent lamps. Despite this, some countries have banned or are about to ban the sale of incandescent lamps due to their high power.

The power of household electrical appliances may differ depending on the manufacturer, and is not always the same when the appliance is in operation. Below are the approximate capacities of some household appliances.

Household air conditioners for cooling a residential building, split system: 20–40 kilowatts
Monoblock window air conditioners: 1–2 kilowatts
Ovens: 2.1–3.6 kilowatts
Washing machines and dryers: 2–3.5 kilowatts
Dishwashers: 1.8–2.3 kilowatts
Electric kettles: 1–2 kilowatts
Microwave ovens: 0.65–1.2 kilowatts
Refrigerators: 0.25–1 kilowatt
Toasters: 0.7–0.9 kilowatts

Power in sports

It is possible to evaluate work using power not only for machines, but also for people and animals. For example, the power with which a basketball player throws a ball is calculated by measuring the force she applies to the ball, the distance the ball has traveled, and the time that force has been applied. There are websites that allow you to calculate work and power during exercise. The user selects the type of exercise, enters the height, weight, duration of the exercise, after which the program calculates the power. For example, according to one of these calculators, the power of a person with a height of 170 centimeters and a weight of 70 kilograms, who did 50 push-ups in 10 minutes, is 39.5 watts. Athletes sometimes use devices to measure the amount of power a muscle is working during exercise. This information helps determine how effective their chosen exercise program is.

Dynamometers

To measure power, special devices are used - dynamometers. They can also measure torque and force. Dynamometers are used in various industries, from engineering to medicine. For example, they can be used to determine the power of a car engine. To measure the power of cars, several main types of dynamometers are used. In order to determine the engine power using dynamometers alone, it is necessary to remove the engine from the car and attach it to the dynamometer. In other dynamometers, the force for measurement is transmitted directly from the wheel of the car. In this case, the car's engine through the transmission drives the wheels, which, in turn, rotate the rollers of the dynamometer, which measures engine power under various road conditions.

Dynamometers are also used in sports and medicine. The most common type of dynamometer for this purpose is isokinetic. Usually this is a sports simulator with sensors connected to a computer. These sensors measure the strength and power of the whole body or individual muscle groups. The dynamometer can be programmed to give signals and warnings if the power exceeds a certain value. This is especially important for people with injuries during the rehabilitation period, when it is necessary not to overload the body.

According to some provisions of the theory of sports, the greatest sports development occurs under a certain load, individual for each athlete. If the load is not heavy enough, the athlete gets used to it and does not develop his abilities. If, on the contrary, it is too heavy, then the results deteriorate due to overload of the body. Physical activity during some activities, such as cycling or swimming, depends on many environmental factors, such as road conditions or wind. Such a load is difficult to measure, but you can find out with what power the body counteracts this load, and then change the exercise scheme, depending on the desired load.

Do you find it difficult to translate units of measurement from one language to another? Colleagues are ready to help you. Post a question to TCTerms and within a few minutes you will receive an answer.

Most of all, in the frosty winter months, all people are waiting for the New Year, and least of all - receipts for heating. They are especially disliked by residents of apartment buildings, who 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 a calorie

Supporters of a healthy diet or those who are closely monitoring their weight are familiar with such a thing as 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 the person will begin to recover.

Paradoxically, the same value is used to measure the amount of thermal energy used for space heating.

As an abbreviation, this value is referred to as "cal", or in English cal.

In the metric system, the equivalent of a calorie 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 the combustible fuel.

In most developed countries, when calculating heating, people no longer pay for the number 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 used for heating. This practice reduces the possibility of diluting the substance used with other, cheaper and less caloric compounds.

Gigacalorie - what is it and how many calories are in it?

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, such a concept as gigacalorie is used. This is a value equal to 10 9 calories, and it is written as an abbreviation "Gcal". It turns out that there are one billion calories in one gigacalorie.

In addition to this value, a slightly smaller one is sometimes used - Kcal (kilocalorie). It holds 1000 cal. Thus, we can consider that one gigacalorie is a million kilocalories.

It is worth bearing in mind that sometimes a kilocalorie is written simply as "cal". Because of this, confusion arises, and in some sources it is indicated that 1 Gcal is 1,000,000 cal, although in reality we are talking about 1,000,000 Kcal.

Hecacalorie and Gigacalorie

In the energy sector, in most cases, Gcal is used as a unit of measurement, but it is often confused with such a concept as "hecacalorie" (aka hectocalorie).

In this regard, the abbreviation "Gcal" is deciphered by some people as "hecacalorie" or "hectocalorie". However, this is wrong. In fact, the above 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 under consideration, receipts sometimes contain such an abbreviation as “Gcal / hour”. What does it mean and how is it different from the usual gigacalories?

This unit of measure shows how much energy was used in one hour.

While simply a gigacalorie is a measurement of heat consumed over an indefinite period of time. It depends only on the consumer what time frame will be indicated in this category.

The reduction Gcal / m 3 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 finding out how to calculate how many gigacalories are used to heat the room during the heating season.

For especially lazy people on the Internet, there are a lot of online resources where specially programmed calculators are presented. It is enough to enter your numerical data into them - and they themselves will calculate the number of gigacalories consumed.

However, it would be nice to be able to do it yourself. There are several formulas for this. The simplest and most understandable among them is the following:

Thermal energy (Gcal / h) \u003d (M 1 x (T 1 -T xv)) - (M 2 x (T 2 -T xv)) / 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 - the temperature of the coolant in the supply pipe, measured in Celsius.
T 2 - the temperature of the coolant in the return.
T xv is the temperature of the cold source (water). Usually equal to five since this is the minimum temperature of the water in the pipeline.

Why housing and communal services overestimate the amount of energy spent when paying for heating

When making your own calculations, you should pay attention to the fact that housing and communal services slightly overestimate the norms for the consumption of thermal energy. The opinion that they are trying to earn extra money on this is erroneous. Indeed, the cost of 1 Gcal already includes maintenance, salaries, taxes, and additional profit. Such a "surcharge" is due to the fact that during the transport of hot liquid through a pipeline in the cold season, it tends to cool down, that is, inevitable heat losses occur.

In numbers, it looks like this. 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 t of water 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 losses, this coefficient is overestimated to 0.059 Gcal.

Convert Gcal to kWh

Thermal energy can be measured in various units, however, 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 ratios of these quantities are known. For example, consider watts (W), which measures the energy output of most boilers or heaters.

Before considering the conversion to this Gcal value, it is worth remembering that, like a calorie, a watt is small. Therefore, kW (1 kilowatt equals 1000 watts) or mW (1 megawatt equals 1000,000 watts) is more commonly used.

In addition, it is important to remember that power is measured in W (kW, mW), but it is used to calculate the amount of electricity consumed / produced. In this regard, it is not the conversion of gigacalories to kilowatts that is considered, but the conversion of Gcal to kW / h.

How to do it? In order not to suffer with 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 amount of Gcal by 1163.

For example, let's convert to kWh 0.05 Gcal required to heat one cubic meter of water by 50 °C. It turns out: 0.05 x 1163 \u003d 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 one.

If we are talking about huge volumes, you can convert not to kilowatts, but to 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 obtained in kilowatts by a thousand.

Translation to Gcal

Sometimes it is necessary to carry out the reverse process, that is, to calculate how many Gcal are contained in one kWh.

When converting to gigacalories, the number of kilowatt-hours must be multiplied by another "magic" number - 0.00086.

The correctness of this can be checked if we take the data from the previous example.

So, it was calculated in it 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 original data.

As in the 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 into gigacalories.

How is it done? In this case, again, you 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 on him that you need to multiply in order to carry out the transfer.

By the way, a slight 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 house, it is better to simplify.

Let's start with the concepts of "work" and "power". Work is a part of the internal energy expended by a person or machine over a certain time period. In the process of such work, a person or machine warms up, releasing heat. Therefore, both internal energy and the amount of heat released or absorbed, 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 internal energy is spent. 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 is the work of an engine, or the work of an electric current). Thermal power is the amount of heat transferred per unit time to the coolant (water, oil) from the combustion of fuel (gas, fuel oil) in the boiler.

The calorie was introduced as early as 1772 Swedish experimental physicist Johann Wilke as a unit of heat. Currently, a unit that is a multiple of calories - gigacalorie (Gcal), is actively used in such areas of life as utilities, heating systems and thermal 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.

Even at school, in physics lessons, we were taught that in order to heat any substance, it needs to be imparted a certain amount of heat. There was even such a formula Q = 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 by 1 degree Celsius at an atmospheric pressure of 101325 Pa."

Since heat is measured in joules, using the formula above, we find out what is 1 calorie (cal) in joules. To do this, take the value of the specific heat capacity of water under normal conditions (atmospheric pressure p=101325 Pa, temperature t=20°C) from a reference book on physics: c=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 equal to 4.1868 J.

Memo 1

1 cal=4.1868 J, 1 kcal=1000 cal, 1 Gcal=1 billion cal=4186800000 J=4186.8 MJ;
1 J=0.2388 cal, 1 MJ=1 million J=238845.8966 cal=238.8459 kcal;
1 Gcal/h=277777.7778 cal/s=277.7778 kcal/s=1163000 J/s=1.163 MJ/s.

gigacalories or kilowatts

Let's finally figure out what is the difference between these units of measurement. Suppose we have a heating device, for example, a kettle. Let's take 1 liter of cold tap water (temperature t1=15°C) and boil it (heat it up to temperature t2=100°C). The electric power of the kettle is P=1.5 kW. How much heat will the water absorb? To find out, we apply the familiar formula, taking into account that the mass of 1 liter of water is m=1 kg: Q=4183 [J/(kg*°C)]*1 kg*(100°С-15°С)= 355555 J = 84922.8528 cal≈85 kcal.

How long does it take for the kettle to boil? Let all the energy of the electric current go to heat the water. Then we will find the unknown time using the energy balance: "The energy consumed by the kettle is equal to the energy absorbed by water (without taking into account losses)". The energy consumed by the kettle during time τ is equal to P*τ. The energy absorbed by water is equal to Q. Then, based on the balance, we get P*τ=Q. From here, the heating time of the kettle will be: τ=Q/P=355555 J/1500 W≈237 s≈4 min. The amount of heat transferred by the kettle to water per unit of time is its heat output. In our case, it will be Q/τ=84922.8528 cal/237 s≈358 cal/s=0.0012888 Gcal/h.

Thus, kW and Gcal/h are power units, and Gcal and MJ are units of heat and energy. How can such calculations be applied in practice? If we receive a receipt for paying for heating, then we pay for the heat that the supply organization supplies to us through pipes. This heat is taken into account in gigacalories, i.e., in the amount of heat consumed by us during the billing period. Should this unit be converted to joules? Of course not, because we're just paying for a specific number of gigacalories.

However, it is often necessary to choose certain heating devices for a house or apartment, for example, an air conditioner, a radiator, a boiler or a gas boiler. In this connection, it is required to know in advance the thermal power required to heat the room. Knowing this power, you can choose the appropriate device. It can be specified both in kW and Gcal / h, as well as in units of BTU / h (British Thermal Unit - British Thermal Unit, h - hour). The following note will help you convert kW to Gcal/h, kW to BTU/h, Gcal to kWh and BTU to kWh.

Memo 2

one W=one J/s=0.2388459 cal/s=859.8452 cal/h=0.8598 kcal/h;
one kW=one kJ/s=1000 J/s=238.8459 cal/s=859845.2279 cal/h=0.00085984523 Gcal/h;
one MW=one MJ/s=one million J/s=1000 kW=238845.8966 cal/s=0.85984523 Gcal/h;
one Gcal/h=one billion cal/h=1163000 W=1163 kW=1.163 MW=3968156 BTU/h;
one BTU/h=0.2931 W=0.0700017 cal/s=252.0062 cal/h=0.2520062 kcal/h;
one W=3.412 BTU/h, one kW=3412 BTU/h, one MW=3412000 BTU/h.

How is the BTU/h unit defined and what is it used for? 1 BTU is the amount of heat required to heat 1 pound of water 1° Fahrenheit (°F). This unit of measurement is mainly used to indicate the heat output of installations such as air conditioners.

Calculation examples

Here we come to the most important thing. How to convert one value to another using the above ratios? Everything is not so difficult. Let's look at this with examples.

Example 1

Thermal power of a copper - 30 kW. What is its equivalent power, expressed in Gcal / h?

Solution. 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. For the purchase, an air conditioner with a capacity of 8000 BTU / h was chosen. Is there enough air conditioner power to cool the office?

Solution. Since 1 BTU/h=0.2931 W, then 8000 BTU/h=2344.8 W=2.3448 kW. This value is less than the calculated value of 2.5 kW, so the selected air conditioner is not suitable for installation.

Example 3

The heat supply organization supplied 0.9 Gcal of heat per month. What power should a radiator be installed so that it gives the same amount of heat per month?

Solution. Let's assume that heat was supplied to the house evenly over one month (30 days), so the heat output supplied by the boiler house can be found by dividing the entire amount of heat by the number of hours in a month: P = 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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All summer long, the red gossips in soft furs sang and danced, and now, when the cold comes, you will have to pick up pencils. After all, "heating, as it was not, and is not." And it is necessary to present at least some arguments of the heating network, having calculated the heat received from it, for which, after all, it was “Paid”.

When you need to dot all the "i"

But a quite reasonable question arises: "But how to calculate what is invisible and capable of escaping in an instant, literally through the window." You should not despair of this struggle with the 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 state utility organizations. As usual in these institutions, there are several such documents, but the main one is the so-called "Rules for accounting for thermal energy and coolant". It is he who will help solve the question - how to calculate Gcal for heating.

Actually, the problem can be solved quite simply and no calculations are needed if you have a meter not just for water, but for hot water. The readings of such a meter are already "filled" with data on the received heat. 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 follow the following formula:

Q = V * (T1 - T2) / 1000

In the formula:

Q is the amount of thermal energy;
V is the volume of hot water consumption in cubic meters or tons;
T1 is the hot water temperature in degrees Celsius. It is more accurate to use the temperature in the formula, but reduced to the corresponding pressure, the so-called "enthalgy". But in the absence of a better - the corresponding sensor, we simply use the temperature, which is close to the enthalpy. Professional heat metering units are able to calculate exactly the enthalpy. Often this temperature is not available for measurement, therefore, they are guided by the constant “from the ZhEKA”, which can be different, but usually is 60-65 degrees;
T2 is the cold water temperature in degrees Celsius. This temperature is taken from the cold water pipe of the heating system. Consumers, as a rule, do not have access to this pipeline, therefore it is customary to take constant recommended values depending on the heating season: in the season - 5 degrees; out of season - 15;
The “1000” factor allows you to get rid of the 10-digit numbers and get data in gigacalories (not just calories).

As follows from the formula, it is more convenient to use a closed heating system, into which the required volume of water is once poured and in the future it does not flow. But in this case, you are forbidden to use hot water from the system.

The use of a closed system makes it necessary to slightly improve the above formula, which already takes the form:

Q = ((V1 * (T1 - T)) - (V2 * (T2 - T))) / 1000

V1 is the flow rate of the coolant in the supply pipeline, regardless of whether water or steam serves as the coolant;
V2 - coolant flow in the return pipeline;
T1 is the temperature of the heat carrier at the inlet, in the supply pipeline;
T2 is the temperature of the coolant at the outlet, in the return pipeline;
T is the temperature of cold water.

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.

Helpful advice! As you can see, there is not much mathematics, but the 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 Microsoft Excel spreadsheet included in the Microsoft Office package. In Excel, you can not only quickly calculate everything, but also “play” with the source data, simulate various situations. Moreover, Excel will help you with the construction of graphs for the receipt - heat consumption, and this is an "unkilled" map in a possible future conversation with government agencies.

Alternatives

As there are various ways to provide housing with heat by choosing a coolant - water or steam, so there are alternative methods for calculating the heat received. Here are two more formulas:

Q = ((V1 * (T1 - T2)) + (V1 - V2) * (T2 - T)) / 1000

Q = ((V2 * (T1 - T2)) + (V1 - V2) * (T1 - T)) / 1000

Thus, the calculations can be done with your own hands, but it is important to coordinate your actions with the calculations of the organizations supplying heat. Their calculation instructions may be fundamentally different from yours.

Helpful advice! Often, reference books provide information not in the national system of units of measure, to which calories belong, but in the international system "Ci". Therefore, we advise you to remember the coefficient for converting kilocalories to kilowatts. It is equal to 850. In other words, 1 kilowatt is equal to 850 kilocalories. From here it is already easy to make the transfer of gigacalories, given that 1 gigacalories 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 does not exceed 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 coolant flow rates, and
100 is the conversion factor to percent.

The percentage of error in the calculation of heat is considered acceptable - no more than 2 percent, given that the error of measuring instruments is no more than 1 percent. You can, of course, get by with the old proven method, here you don’t need to do any calculations.

Representation of received data

The price of all calculations is your confidence in the adequacy of your own financial costs for the heat received from the state. Although, in the end, you still will not understand what Gcal is in heating. Hand on heart, let's say that in many ways this is the value of our sense of self and attitude to life. Some base "in numbers", of course, you need to have in your head. And it is expressed in what is considered a good norm, when your formulas give 3 gcal per month for an apartment of 200 square meters. Thus, if the heating season lasts 7 months - 21 Gcal.

But all these quantities are rather difficult to imagine “in the shower”, when warmth is really needed. All these formulas and even the results they give you correctly will not warm you up. They will not explain to you why even at 4 Gcal per month, you are still 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 here - his atmosphere is also warmed by the warmth of those around him, and you don’t have anyone to snuggle up to, 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 until the last under the covers. Warm yourself from the inside, hang photos of the family on the wall - everyone in swimsuits on the beach in Foros in the summer, watch the video of the last ascent to Ai-Petri more often - everyone is naked, it's hot, then outside you won't even feel a lack of a couple of hundred calories.