Determination and Application of Comprehensive Specific Frictional Resistance in Heating Engineering

Table 1

Duration of outdoor temperature in Zhangjiakou.

Number	Outdoor temperature (°C)	Duration of outdoor temperature (hours)
	>5	4728
	5	4032
	4	3850
	3	3667
	2	3483
	1	3299
	0	3114
		2927
		2740
		2552
		2363
		2173
		1981
		1788
		1593
		1397
		1197
		996
		790
		579
		361
		120