CN102565123A

CN102565123A - Method for measuring air ratio and heat capacity ratio by adiabatic compression as well as modifying data

Info

Publication number: CN102565123A
Application number: CN2011104234527A
Authority: CN
Inventors: 李娟�; 胡再国
Original assignee: Sichuan University
Current assignee: Sichuan University
Priority date: 2011-12-16
Filing date: 2011-12-16
Publication date: 2012-07-11
Anticipated expiration: 2031-12-16
Also published as: CN102565123B

Abstract

The invention discloses a method for measuring air ratio and heat capacity ratio by adiabatic compression as well as modifying data and relates to the field of physical parameter measurement. For experiments of students, a plurality of data are required to be measured within 3-4 hours, so that the heat insulating effect of a container accommodating the air is poor, the heat insulating effect is poor and the pumping speed is extremely low; and the air ratio and the heat capacity ratio are generally measured by adopting an adiabatic expansion method and cannot be measured by adopting the adiabatic compression. Due to the influence from non-heat-insulating factors, measurement values of the air ratio and the heat capacity ratio are extremely small. The invention adopts the technical scheme that quick pumping is realized by reducing the volume of a gas container and high-speed sampling and data modification are subsequently carried out. The method for measuring the air ratio and the heat capacity ratio by the adiabatic compression, which is disclosed by the invention, is beneficial to the understand of the students and the guidance of the students understanding the influence on experimental data caused by heat radiation and a processing method thereof, so that the students can better understand air ratio and heat capacity ratio parameters, and a scientific data processing method is preliminarily established.

Description

Adiabatic compression Measurement of Air specific heat capacity is data correcting method when

Technical field

The present invention relates to the physical parameters measurement field, particularly the measurement of physical parameter air ratio ratio of specific heat.

Background technology

The measurement of physical parameter air ratio ratio of specific heat is the classical experiment of of most of universities; The time restriction of student experimenting roughly 3-4 hour, measure a plurality of data; Then the insulation effect of the container of splendid attire air just can not be very good, otherwise time-consuming very, container generally adopts glass material; Because insulation effect is not good too slow with the speed of inflating; Generally all adopt the method for adiabatic expansion to measure at the Measurement of Air specific heat ratio,, generally all adopt bigbore venting valve to shorten deflation time in order to reduce the influence that nonadiabatic factor is brought.Can not realize that adiabatic compression comes the Measurement of Air specific heat ratio.

Because the influence of nonadiabatic factor, cause the measured value of coefficient of air ratio ratio of specific heat less than normal.

Summary of the invention

Realize that adiabatic compression comes the Measurement of Air specific heat ratio, then subject matter is to shorten to inflate the time, and dwindling volume of a container is exactly a way.

The technical scheme that the present invention solves its technical matters employing is: get the happy 500 milliliters of water tumblers buckleing sealing of rigid plastic band; The hole of boring a 4mm respectively at the bowl cover and the cup end; A hole connects and inflates, and a hole connects the barometric surveying device, notices that each device can not have gas leakage.

Obtain experimental data through experiment, table 1 is an example of experimental data.

The data correction reason: the pressure 10.8hPa of sensor measurement is the pressure reduction of room pressure relative standard air pressure; 0.21 second consuming time of the maximal value 95.3hPa that inflates (from 1.67 seconds to 1.88 seconds); Pressure reduces 95.3-89.1=6.2hPa when dispelling the heat 0.21 second (from 1.88 seconds to 2.09 seconds) from maximal value 95.3hPa; Have reason to believe that the maximal value 95.3hPa that in the 0.21 second time of inflating, also has heat radiation to cause measuring is littler than actual maximal value.

Data correcting method: the method match of employing fitting of a polynomial drops to 89.1hpa from 1.88 seconds to 2.09 seconds the pressure that causes because of heat radiation from 95.3hPa, obtains polynomial expression.The air pressure recruitment of supposing each sampling time interval is exactly the inflate quantity in this sampling time; Calculate this inflate quantity and use the polynomial computation pressure values that 1.88 seconds corresponding sampling times are reduced from the sampling time to maximum gas pressure 95.3hPa, all are inflated the reduction pressure values of sampling time after by polynomial computation add up to total correction.

This experimental data result of calculation is: the corresponding polynomial expression of quadratic power match is y=84.5 (1-0.5699t+1.195*t*t); Wherein y is indoor relatively pressure difference; T is the time difference with respect to 1.88 seconds; 84.5 indoor relatively pressure difference when being 1.88 seconds, correction formula in time is 1-0.5699t+1.195*t*t; Modified value 84.5-80.86=3.64hpa.The calculated value of air ratio ratio of specific heat=(95.3-10.8+3.64)/(72.4-10.8)=1.42 more approaching with theoretical value 1.402.

The invention has the beneficial effects as follows: help students understand is come the Measurement of Air specific heat ratio through adiabatic compression method; Help guiding student and understand influence and the disposal route thereof of heat radiation experimental data; Make the student can understand air ratio ratio of specific heat parameter better; Tentatively set up the data processing method of science, be good at from data, seeking rule.

Table 1 experimental data

The pressure that table 2 process of inflating causes because of the heat radiation correction that diminishes

?t_sample(s)	P(hPa)	t_delta(s)	P_delta1(hPa)	P_delta2(hPa)
					1.67	10.8	0.21	0	0.00
1.68	12	0.2	1.2	1.12
					1.69	14.9	0.19	2.9	2.71
1.7	18.6	0.18	3.7	3.46
					1.71	22.7	0.17	4.1	3.84
1.72	27.1	0.16	4.4	4.13
					1.73	31.9	0.15	4.8	4.52
1.74	36.7	0.14	4.8	4.53
					1.75	41.9	0.13	5.2	4.92
1.76	47	0.12	5.1	4.84
					1.77	52.2	0.11	5.2	4.95
1.78	57.5	0.1	5.3	5.06
					1.79	62.9	0.09	5.4	5.18
1.8	68.1	0.08	5.2	5.00
					1.81	73.1	0.07	5	4.83
1.82	77.9	0.06	4.8	4.66
					1.83	82.5	0.05	4.6	4.48
1.84	86.5	0.04	4	3.92
					1.85	90	0.03	3.5	3.44
1.86	92.8	0.02	2.8	2.77
					1.87	94.7	0.01	1.9	1.89
1.88	95.3	0	0.6	0.60
								84.5	80.86

Claims

1. adiabatic compression Measurement of Air specific heat capacity of the present invention when data correcting method relates to physical parameters measurement; The design of air inclusion container, inflate, measurement and data correction; It is characterized in that: (1), get the happy 500 milliliters of water tumblers buckle sealing of rigid plastic band, in the hole that a 4mm is bored at the bowl cover and glass end respectively, a hole connects inflator; A hole connects the barometric surveying device, notices that each device can not have gas leakage; (2), the pressure change after high speed is obtained the pressure change of inflating and beaten gas; (3), use the pressure change rule inflate after accomplishing to revise to inflate the minimizing of the pressure that the heat radiation of interlude internal cause causes.