[Mechanical Equipment Technology Edition] Daily Question 20170807: Refrigeration Principles (3)
Thread Content
Starting today, in order to enhance communication among those interested in marine equipment, we have launched the 【Question of the Day】 campaign on the Technical Forum for Moving Equipment. We encourage everyone to participate actively so that we can all progress and improve together! ! ! Rewards: 3 wealth for active participation, 10 wealth for correct answers. This question is valid for two days; no scoring will be given after that. Title: The figure below shows the pressure-enthalpy diagram most widely used in refrigeration; analyze the thermodynamic processes of compression and condensation based on this diagram. http://p1.so.qhimgs1.com/t01e5e56369de0b6c61.jpg Answer: Content hidden in this post Content hidden in this post Content hidden in this post Content hidden in this post Content hidden in this post Compression: Isentropic adiabatic compression; Condensation: Isothermal isobaric heat release ================================ Promotion event: Petrochemical sector – “Creative Ideas for Energy Saving” campaign (the second phase of this campaign is currently in progress) http://bbs.hcbbs.com/thread-1666758-1-1.html (Source: Haichuan Chemical Industry Forum) 2017 Coal chemical industry – “My Technical Upgrades” http://bbs.hcbbs.com/thread-1786290-1-1.html (Source: Haichuan Chemical Industry Forum)
In the system, the compressor is responsible for compressing and transporting the refrigerant vapor, which results in low pressure in the evaporator and high pressure in the condenser. It is the heart of the entire system ； The expansion valve (throttle valve) thins and reduces the pressure of the high-pressure liquid refrigerant, while also regulating the flow rate of this refrigerant as it enters the evaporator ； The function of the evaporator is to generate cold air; the refrigerant absorbs heat from the medium to be cooled within the evaporator, thereby achieving the purpose of producing cold air ； The condenser is responsible for outputting
Compression: isentropic adiabatic compression; Condensation: isothermal isobaric heat release.
Compression: Temperature and pressure increase. Condensation: Pressure remains constant while temperature decreases
Compression: Temperature and pressure increase. Condensation: Pressure remains constant while temperature decreases
Compression: Temperature and pressure increase. Condensation: Pressure remains constant while temperature decreases
This post was last edited by Peng Zuosen on 2017-8-8 at 13:38. Compression: isentropic adiabatic compression; Condensation: isothermal isobaric heat release
The refrigerant absorbs heat from the medium being cooled in the evaporator, boils at pressure P0 and temperature t0, reaching state point 1, which is a saturated vapor state. Before the compressor continuously draws in the vapor generated in the evaporator, in order to prevent liquid droplets from entering the compressor, the refrigerant usually continues to absorb some heat even after it has completely evaporated in the evaporator; in fact, what the compressor draws in is superheated saturated vapor, and the process from 1 to 2 represents the superheating stage. Point 2 is the compressor suction point. Passing through point 2, the compressor compresses the superheated steam to reach point 3. Due to the compression work performed by the compressor, the pressure of the refrigerant vapor rises to Pk and the temperature increases to t3; the process from 2 to 3 represents the compression stage.
Isentropic dry compression, isobaric heat release.
The heat released by 1 kg of refrigerant during cooling and condensation, in kJ/kg. qk = h2 – h3: The compression work required by the compressor to compress and transport 1 kg of refrigerant, in kJ/kg. w0＝h2－h1
1-2 Adiabatic compression process 2-3 Isobaric heat release process