Among some small commercial users, many gas stoves, boilers and water heaters are very similar to civil use, but with larger capacity. Natural gas heating systems are usually installed on the roofs of commercial buildings. These rooftop facilities also tend to be "integrated" and "easy to package" rather than large central heating systems. Similar to stoves, facilities on the roof have become more efficient and easy to install, and some manufacturers have provided some adjustable gas stoves (Figure 7.7).
Figure 7.7 Trane Roof Heating Facility (photo approved by Natural Gas Research Institute)
The heating of water is the second largest field of commercial gas. In the United States, about 80% of commercial water heaters are driven by natural gas. Natural gas heating water is particularly popular in commercial places that need a lot of hot water, such as laundries and beauty salons. In restaurants, gas-fired water heaters are used to raise the temperature of dishwashing water to meet the standards stipulated by government decrees.
Cooking gas in restaurants, hospitals and schools is increasing, and it has become the third largest market for commercial gas. Many kitchen owners can only cook with natural gas, and some expensive residential areas also use some commercial natural gas. Special natural gas cookers in commercial restaurants include a combination of several stoves, a "shell" (double-sided) grill/shallow pot and a conventional stove. Gas stoves are specially designed for fast food restaurants, including large-capacity frying pans (Figure 7.8) and shallow pans. The natural gas industry makes these cookers easier to operate, so employees of fast food restaurants can actually operate them with little training.
Fig. 7.8 Frymaster large-capacity frying pan (photo approved by Natural Gas Research Institute)
Natural gas refrigeration
Different from civil natural gas, many large commercial buildings use natural gas to regulate air like heating. Central cooling water system is usually used in hospitals, university campuses and office buildings. Most refrigerators powered by natural gas use adsorption principle to produce cooling water for air conditioning (Figure 7.9). These refrigerators are characterized by quiet and trouble-free operation. Compared with electric refrigerator, the absorption part of natural gas refrigerator is cooled by water, which replaces those chemicals that can cause global warming. Because the government has restricted the use of these chemicals, some refrigerators are being replaced by natural gas refrigerators.
Figure 7.9 York Millennium Natural Gas Refrigerator (photo approved by Natural Gas Research Institute)
Other commercial natural gas air conditioning methods are engine-driven refrigerators. Natural gas engines have been used to power refrigeration for many years, but only recently have major changes taken place, and efficient and compact systems have been realized and become popular. The principle of refrigeration driven by natural gas engine is simple-replacing the motor in conventional refrigerator with natural gas engine. This engine provides power for the compressor, which can produce cooling water. In air conditioning equipment, natural gas engine has more advanced characteristics than electric motor. For example, this kind of engine can be adjusted according to the needs of the building to improve the cooling efficiency. In addition, the heat generated by the engine can be recovered to generate hot water for other buildings.
Generally speaking, buying a refrigerator driven by natural gas is more expensive than buying a refrigerator driven by a conventional motor, but the operating cost is lower than the latter. Motors used by commercial users need to spend a lot of money during the day or in summer. Even if there are irregularities in the electricity market, most industrialists are still reluctant to lower the electricity price at the peak of demand.
By reducing the peak electricity consumption cost, the refrigerator powered by natural gas can reduce the energy expenditure of commercial users and the cost of public facilities. Managers of some commercial buildings are installing a "hybrid" air conditioning system, which uses a mixture of natural gas and electric refrigerators. The choice of these facilities depends on the price ratio of natural gas to electricity in a specific time. Usually, natural gas refrigerators can be used during the day, when the electricity price is high, and refrigerators can be used during "off-peak" hours at night. Recently, a refrigerator manufacturer introduced a hybrid device-combining a natural gas engine and an electric motor.
In addition to air conditioning, the concept of "natural gas refrigeration" is also applicable to refrigerators with low temperature requirements. Similar to refrigerators, refrigerator systems can also be driven by natural gas. These advances in refrigerators are similar to air conditioners, and the main purpose is to reduce electricity bills. The user's building system has also formed some standard models.
The earliest refrigerators powered by natural gas appeared in the market were ice making, skating rink, wine making, beverage making, meat packaging and refrigeration (refrigeration). In 1990s, natural gas refrigerators were more widely used in other food processing machinery.
Air dehumidification
Another growth point of commercial natural gas is air dehumidification, that is, dehumidification before air enters the heating and cooling system of buildings from the outside. In the 1980s, there was little ventilation in commercial buildings. In order to save energy, the air in the whole building is recycled, and only a little outdoor fresh air is mixed. However, people soon realized that this practice is very unfavorable to indoor air quality, making the air dirty or even turbid. Therefore, poor quality ventilation equipment often leads to "office syndrome". In these buildings, chemicals in carpets and other furniture are mixed into the circulating air, which will lead to headaches and other comprehensive diseases.
Recently, the heating and air conditioning industry has changed the ventilation standards officially announced in the past. Improving indoor air quality requires introducing three fresh air. However, people haven't designed and used electric air conditioning system to inhale so much fresh indoor air for air exchange, especially in those areas with high humidity. The traditional electric air conditioner removes moisture from indoor air by adsorption, which needs to cool the air to a very low temperature and then heat it to a suitable temperature. Obviously, this is a very inefficient way.
This is the reason why the natural gas dehumidifier appeared. Over the years, the natural gas industry has developed a variety of air dehumidification systems. These systems use desiccant (such as silica gel) to remove moisture from the air by adsorption. The heat of natural gas can be used to "regenerate" these desiccants or restore their ability to absorb water. These early natural gas dehumidification systems were first used in supermarkets and hospitals. In these places, the condensed water in the air conditioning system will cause high cost and even indoor insecurity.
With the change of ventilation standard, natural gas drying system is becoming more and more popular (especially in humid climate areas). In most cases, they are used for "pretreatment" of air before it enters the air conditioning system (evaluating the humidity and temperature of air). At present, a large number of products have been developed and sold, including single ventilation facilities and complex ventilation systems, which can recover the energy of air discharged from buildings for regenerative drying (Figure 7. 10). Some similar ventilation products have been used to replace the traditional electric air conditioner on the roof.
Fig. 7. Schematic diagram of10 drying energy recovery system (SEMCO license) S-summer; winter