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Application Test of the Invotech Scroll Compressor in Last Heating Season

Pubdate:2018-02-08 09:33Writer:adminClick:
The monitoring data is as following: (The data was collected and published by Invotech)
INVOTECH-“Coal to electricity” data collection information
Date of collection 15, November, 2016-22, March,2017
Monitoring location A household in Tongzhou District, Beijing
Heating unit modle ZGR-17ID 6HP
Scroll compressor model INVOTECH YW75A2-V102 * 2 sets
Heating type Radiator
Heating area 120㎡

The performance of the heating unit during the coldest period

We selected 3 days from the coldest period of the 2016-2017 heating year in Tongzhou District, from December 22, 2016 to December 24, 2016. The data shows that the average daily temperature during the three days is -5°C ~ -6.3°C, the lowest temperature is -12.2 °C, the highest temperature is 2.9 °C, the indoor temperature is always maintained at 18.5~21.2 °C, the heating unit’s outlet water temperature is 43~48°C, the return water temperature is 41~45°C, the temperature difference between the outlet and return water is basically stable at 3 °C, and the discharge temperature of the compressor is up to 103.6 °C.

 Indoor temperature of the coldest time period from December 22 to 24, 2016 (18.5~21.2℃)

The return water temperature of the heating unit during the coldest period from December 22 to 24, 2016 (41~45°C)

 Compressor discharge  temperature (<103.6 °C) for the coldest period from December 22 to 24, 2016

Effect of ambient temperature change on heating unit’s operation and heating efficiency

Taking December 2016 as an example, selecting the day with the highest average temperature (December 1, the average daily temperature is 5.0 °C), and the day with the lowest average temperature (February 30, the average daily temperature is -5.3 °C), the daily average temperature difference between the two days is 10.3 °C, but the indoor average temperature difference was only 2 °C. It can be seen from the curve that as the outdoor temperature rises, the indoor temperature will also increase; the outdoor average temperature difference is large, but the effect on the indoor temperature is small, because the user's house walls and windows are insulated. The house is equivalent to large heat storage and heat preservation equipment. At the same time, the heating unit's start-up time (heating time) is increased by 66.7%, the stop interval is reduced, and the total start-stop cycle time is basically the same. Reflecting the heating time of the unit under low ambient temperature, the power consumption will increase significantly.
 
Above data is completely collected from the user's actual using situation, according to the user's life schedule and usage habits, between 11:00 and 17:30, the user may go out or shut down the heating unit due to the outdoor temperature is high, therefore, the unit was shut down during this time, so the indoor temperature dropped. Even if heating system is stopped, the indoor temperature is maintained above 17.5 °C, which shows that the heat conservation of user’s house is very good.

 Effect of highest temperature and lowest temperature on the indoor temperature, in December 2016
(User turns off the heating unit; the temperature is high from 11:30 to 17:30,)

▲ Effect of the highest and lowest temperatures on heating unit’s opening and shutdown at in December 2016

Effect of defrosting on heating unit operation and heating effect

We selected the day of heavy smog on December 19, 2016, when Beijing issued a warning of smog orange and carried out traffic restrictions. Due to the low temperature in the north and the smoggy and snowy weather, it is easy to cause large-area frosting of the air source heat pump evaporator, which affects the heating effect. From this monitoring, the weather with heavy smog is selected, and the humidity is high. At the same time, the temperature of -4 °C ~ 8 °C is also the stage where the heating unit is easy to frost. The following figure shows the defrosting is totally 5 times throughout the day, and the frost can be completely removed after 4 minutes. There is no change in the indoor temperature before and after defrosting, and the indoor temperature is maintained at 18~21 °C throughout the day. Before and after defrosting, the unit's outlet water temperature decreased by 11.4 ° C, the return water temperature only decreased by 2 ° C, and the water temperature returned to the normal level after 9 minutes,. This is because the unit is equipped with a buffer tank, which effectively alleviates the problem that the heating unit does not heat during the defrosting period, and absorb part of the heat from the indoor radiator.


▲ Defrost times

▲ The effect of defrosting on indoor temperature (indoor temperature is 18~21 °C, no change before and after defrosting)

▲ The effect of defrosting on the return water temperature of the unit (before and after defrosting, the unit's outlet water temperature decreased by 11.4 °C, the return water temperature only decreased by 2 °C; after the defrosting, the water temperature returned to the level after 9 minutes)
 
Economical assessment
Beijing 2016 to 2017 heating season coal to clean energy charge policy: heating period from November 1 to March 31, daily from 6 am to 9 pm, peak price is 0.483 CNY/ kWh; From 9:00 pm to 6:00 pm, in the valley price is 0.3 CNY/kWh. The government subsidizes the electricity valley price by 0.1 CNY/degree, and the limit is 10,000 degrees, that is, the electricity price in the valley section is decreased by 0.1 CNY/kWh. (The total power consumption in the heating season exceeds 10,000 kWh, valley price will no longer be subsidized, and the price will rise sharply!). From the table below, it can be seen that the air source heat pump heating efficiency is as high as 290%, which is equivalent to coal heating cost, or even slightly lower, and
saves 70% of the electricity cost compared with electric heating.

Heating method Unit Price/kWh Total heat(kWh) Total electricity(kWh) Heating efficiency Total cost(CNY)
Coal burning 600CNY/Mt(coal) / 3.5-4Mt  30-40% 2100-2400
Air source heat pump Perk 0.483 CNY
Valley 0.1 CNY
20860 Total 7193
Perk 3848
Valley 3345
290% 2193
Electric Perk 0.483 CNY
Valley 0.1 CNY
20860 Total 7193
Perk 3848
Valley 3345
100% 7370

Conclusion
According to the real-time field monitoring data of the entire heating season in Tongzhou District, the operating temperature of the heating unit in this heating season is highly efficient and meets the heating requirements. The analysis results are as following:
(1) During the entire heating season in Beijing, even if the minimum outdoor temperature reaches -12 °C, the indoor temperature can be maintained at 18~21 °C;
(2) When the outdoor temperature is lowered and the indoor temperature is slightly reduced, the user can appropriately increase the temperature of the heating unit to improve the comfort level of the room;
(3) Air source heat pump has obvious advantages compared with traditional coal-fired and electric heating. The total electricity consumption in the heating season is 7193 kWh, and the total heating efficiency is up to 290%, which is energy efficient and saving.



Invotech was honored as the “Excellent Parts and Accessories Suppliers” of Beijing “Coal-to-Clean Energy” air source heat pump industry in 2016. This glory is affirmation of our contribution to “coal to electricity” project in 2016, and also the expectations for future development!