Charging method of air conditioning charging system

Central air conditioning is generally an air conditioning system that uses water as the medium to exchange energy between user terminals and energy centers to realize centralized cooling (or heating). Centralized energy supply and decentralized use are the main characteristics that distinguish central air conditioners from household air conditioners. Because central air conditioning is centralized energy supply and decentralized use, if the decentralized users are different, it will involve the problem of cost sharing, so this paper focuses on several charging methods of central air conditioning.

The simplest charging method of central air conditioning is to share or contract by area, which originated from the heating cost of central heating during the planned economy period and is also the most wasteful and unfair charging method. Because of its deviation from the laws of market economy, the contradiction of charging has intensified from time to time. Central air-conditioning adopts household metering and charging by volume, which fully embodies the basic attributes of energy commercialization of "whoever consumes pays" and "how much energy is used", and has the following significance:

1, household measurement, charge by quantity, fair and reasonable!

2. Encourage users to actively save energy, cultivate energy-saving habits and benefit the country and the people!

3, reduce operating costs, extend the life of the host, and achieve a win-win situation for the owner and the property!

4. Realize the active and passive energy saving of the system and improve the level of property management.

"Commercialization" of energy and charging by quantity are the basic requirements of market economy. In order to realize charging by volume, central air conditioning must have corresponding measuring instruments and methods. According to the different measurement methods, there are the following ways:

1, directly measuring "acclimatization"

The measuring instruments of central air conditioning in the form of direct measurement are mainly electric energy meters. At present, only the electric energy meter developed in heating metering in recent two years is called the metering device of central air conditioning. Because of the great difference between the huge temperature difference of heating and the small temperature difference of central air conditioning, the electric energy meter for measuring heating (accuracy 3-95℃) can not meet the measurement accuracy (0.5℃) requirement of central air conditioning. Moreover, the cost of electric energy meter is too high (minimum model DN20 is about 1 1,000 yuan), and the design of air conditioning system needs to be changed in application, which is easy to cause inaccurate temperature measurement and human error in installation, high water quality requirements for central air conditioning system, and easy to cause faults such as dirty blockage and moisture in use, which is not conducive to the application and promotion of electric energy meter.

According to the principle of conservation of energy, the heat exchange capacity of central air conditioning to space is equal to the energy change in its medium. The watt-hour meter quantifies the central air conditioning by directly measuring the energy change of the central air conditioning medium (chilled water). Its working principle is to calculate the thermodynamic formula Q = ∫ C δ TV = ∫ C (T2-T 1) Qt according to the heat exchange energy of matter. The electric energy meter consists of three parts: a flowmeter with signal output, two temperature sensors and an energy integrator. It measures the instantaneous flow rate and temperature difference of the medium (chilled water) in the central air conditioning system, and calculates the heat exchange capacity of the system through the energy integrator.

This central air-conditioning charging method has clear principle, intuitive results and easy understanding. Because it needs to measure many parameters, especially in the environment of large flow and small temperature difference of central air conditioning system, it requires high temperature difference accuracy of electric energy meter, so its production cost is high. At the same time, it changes the system design and the requirements for the water quality of central air conditioning, which limits its wide use, and is mainly used for layered and partitioned charging of central air conditioning.

Some manufacturers of heat meters add the function of "weighting" to the energy integrator of their own heat meters, thinking that it can be used to charge for central air conditioning, which is a misunderstanding. Although the metering principle of heating and central air conditioning is the same, the actual application environment is different: heating adjusts the heat exchange capacity by adjusting the water flow, which is a small flow and large temperature difference environment. The temperature difference between inlet and outlet water is about 35℃, which requires higher flow accuracy and lower temperature difference accuracy, so the standard temperature difference accuracy of heat meter is 3-95℃; At the end of the central air conditioner is a constant current small temperature difference system, which changes the heat exchange area by adjusting the wind speed, thus achieving the purpose of adjusting the heat exchange capacity! Therefore, it requires low flow accuracy but high temperature difference accuracy. Because the standard temperature difference between the inlet and return water of the central air conditioner is 5℃, if the error of 65438 0℃ is allowed, it can no longer meet the measurement requirements under the condition that a family has six fan coils. Therefore, the temperature difference accuracy of the electric energy meter used for central air conditioning billing should be below 65438 0℃. At present, the temperature difference accuracy of heating heat meters is mostly 2-3℃, and the price has been 1000 yuan. It will cost more to measure the temperature difference accuracy of central air conditioning. Therefore, although the charging technology of central air conditioning based on watt-hour meter is relatively mature, its application cost is too high, which is difficult to be accepted by merchants and consumers.

2. The metering charge of central air-conditioning water meter and electric meter is unreasonable!

In central air-conditioning, direct charging is unacceptable to users because of its high price and inconvenient application, and some seemingly simple and cheap indirect charging methods have appeared. For example: electricity meter billing, water meter billing, etc.

Electricity meter charging is to measure the electricity consumption at the end of the user's air conditioner with an electricity meter as the basis for charging the electricity consumption of the user's air conditioner; If you charge by electricity meter: you can install the refrigeration host, water pump and pipeline in the central air conditioning system! As long as there is electricity, users will definitely charge when they turn on the indoor fan coil! Even if the air-conditioning host in the energy center is not running or there is no air-conditioning host at all, as long as the user's air-conditioning terminal is turned on, there will be a charge.

The hot water meter charge is to charge the user's air conditioning terminal water consumption through the hot water meter as the basis of the user's air conditioning consumption. According to this method, the central air conditioning system only needs to be equipped with water pump, pipeline and indoor fan coil, and any refrigeration host and fan coil power supply can be omitted, and the water pump hot water meter can be charged!

Therefore, whether the central air conditioner is charged by water meter or electricity meter, it can't really reflect the essence of "quantity" of air conditioner. The "quantity" of central air conditioning is the energy consumed (heat exchange capacity). This absurd result is obviously unreasonable, which is also an inevitable phenomenon.

3. The charging method of terminal switching time fails to ensure the inevitable connection between the "amount of time" and "cooling capacity" of central air conditioning, repeating the mistakes of water meter charging and electricity meter charging.

In the case that water meter charging and electricity meter charging are obviously unreasonable and have to be adopted temporarily, it has become the unremitting pursuit of people of insight in the industry to find an economical and practical central air-conditioning metering and charging method that conforms to the domestic application of central air-conditioning. Charging according to the most familiar time seems to be the best solution. However, it is not simple to understand the relationship between time and the "quantity" and "quality" of central air conditioning. The essence of "quantity" of central air conditioning is not grasped, but the opening and closing time of fan coil at the end of central air conditioning is calculated, but the inevitable result of this "quantity of time" and "cooling capacity" of central air conditioning cannot be guaranteed. Charging the central air conditioner according to this "amount of time" has returned to the strange thing that as long as the fan coil unit runs, it can be charged without the host and system! It is not surprising that we are caught in the same situation as water meter metering and electricity meter charging. Why does the national metrology department only issue the License for Manufacturing Measuring Instruments to these manufacturers, but not to the central air-conditioning charging system? (because it implements the electronic clock timer standard)

4. Equivalent energy measurement method The "quantity" to be measured by central air-conditioning is neither water quantity nor electricity quantity, nor time quantity, but the change quantity of energy (cold or hot) carried in the medium water of central air-conditioning. The reason why ——CFP series central air-conditioning billing system can be recognized by the national metering department is because:

The metering and charging of central air-conditioning is to commercialize the energy of central air-conditioning. The price of goods depends on the internal quality and external quantity of goods, while the charging method of water meter, electric meter and terminal switching time only measures the external quantity of central air-conditioning terminals, ignoring the internal quality of central air-conditioning, and the electricity consumption and water consumption of users using air-conditioning terminals. Therefore, it is reasonable for these central air-conditioning charging methods to be eliminated by the market.

CFP series central air-conditioning billing system (effective timing type) firstly detects the water supply temperature of central air-conditioning according to the actual application of central air-conditioning, and only charges when the water supply temperature is greater than 40℃ (heating) or less than 12℃ (cooling) (to ensure the central air-conditioning is "effective"). Then, the state of the electric valve (no valve is considered as normally open) and the motor state of the fan coil are detected for timing (measuring the "effective" use time of the user's fan coil), but this is only a preliminary data. Using computer technology, microelectronics technology, communication technology and network technology, the payment ratio of "equivalent energy" can be reasonably calculated according to these data.

CFP series central air-conditioning billing system is the latest generation of central air-conditioning metering instrument with fan coil as the billing object. It is the crystallization of "effective" charging principle and "timed charging" method initiated by Zhengzhou Chunquan HVAC Energy Saving Equipment Co., Ltd., including CFP charging device, CRS485-D area manager, CJ-Wxp management software and CJ-3000 charging host.

The thermodynamic formula Q = ∫ C δ TV = ∫ C (T2-T 1) Qt is calculated according to the heat exchange energy of matter. The flow Q of the fan coil of central air conditioning is basically constant, and the time T can be measured by a timer. Temperature difference (T2-T 1) is the key point of technology. There are three ways of material heat exchange: conduction, convection and radiation. The heat exchange of central air conditioning fan coil is mainly realized by conduction, without convection, radiation can be ignored. Conduction is proportional to temperature difference and heat exchange area, and the heat exchange area of fan coil is proportional to air flow. V. Under standard temperature and pressure (water supply temperature t1= 7℃; When the return water temperature is T2= 12℃), the formula for calculating the heat exchange capacity of the fan coil of central air conditioner Q = ∫ cδ TV = ∫ c (T2-T 1) Qt can be changed to Q=∫Xvt, (v: wind speed coefficient; X: model capacity coefficient; T: use time). According to the fuzzy theory, we regard the water supply temperature T 1≤ 12℃ (cooling) or T≥40℃ (heating) as an effective metering charge. Water supply temperature t1> 12℃ air conditioner takes the time with poor effect as the loss input cost and does not charge the user fee, which is the "effective" charging principle. The equivalent energy consumed by each fan coil of central air-conditioning is calculated by measuring the running time of each gear under "effective" conditions (the running time of open valve gear) according to W=∑Pi*ti, and the unit price of equivalent energy is equal to the total cost divided by the measured total equivalent energy, so that the unit price multiplied by the consumed equivalent energy can get the central air-conditioning fee that each user should pay. Just like a 1KW electric furnace, 1 hour needs 1 kwh of electricity, but the premise is that the voltage is within the range of 220v 5%, which is an "effective" range that can basically meet the normal use requirements of users. If the voltage exceeds this range, the user's electrical appliances will not work normally.

CFP series central air conditioning billing system not only measures the "quantity" (user use time) of central air conditioning, but also measures the "quality" (effective time) of central air conditioning! Better solve the rationality of central air-conditioning charging, ensure the practicability of central air-conditioning "refrigeration capacity" as a commodity, meet the normal use needs of users, and better protect the rights and interests of users; At the same time, it will supply water temperature t >；; 12℃ or t

CFP series central air-conditioning billing system has good applicability, has no special requirements for the design and installation of central air-conditioning system, and meets the needs of users with low investment cost. It has been widely used in residential buildings and office buildings with fan coil units as the end. The system has the management functions of charging, inquiring and stopping users' air conditioning arrears.

The error influencing factors of CFP series central air conditioning billing system are mainly the imbalance of water flow in central air conditioning system and the inconsistency of heat exchange power of fan coil, which is the core content of our central air conditioning designer's professional design. CFP central air-conditioning charging method is indirect measurement and equivalent sharing mechanism to realize the metering and charging of central air-conditioning! The billing error of CFP series central air conditioning billing system has met the metering accuracy requirements of central air conditioning after secondary deployment in the system. In 2002, CFP series central air-conditioning billing system was approved by the national measuring instrument type and measurement production license, and it was the first special measuring instrument for central air-conditioning approved by the national competent department in China.

Two. abstract

To sum up, the two recommended metering methods are direct electric energy metering (electric energy meter) and CFP equivalent electric energy metering. According to their different characteristics, the former is suitable for large-area measurement such as stratification and zoning, while the latter is suitable for small-area measurement such as office buildings, offices, hotels and houses.

Management suggestion

As a fair and reasonable measuring instrument listed in the national licensing management system, the competent department should strengthen supervision and punishment according to the existing national legal systems such as metrology law, product quality law and consumer rights protection law, and guide the market to develop on the right track. As a real estate developer or system integrator, you should pay attention to the following aspects when choosing such products:

1. Check the manufacturer's qualification, especially the metering license, to see if there is a metering license, and whether the content is central air-conditioning metering instruments.

2. Refuse to replace measuring instruments, and be responsible for users and themselves.

3. Check the measurement standard to see if it meets the measurement requirements.