Device for measuring trans-critical cycle heat exchange of CO2-oil mixture

Abstract

The present invention relates to a device for measuring trans-critical cycle heat exchange of CO2-oil mixture in the technical field of refrigeration and air conditioning. A condenser is sequentially connected with a second electronic expansion valve, a sixth stop valve and an evaporation bypass section which is connected between a third stop valve and a compressor module oil path; the condenser is also sequentially connected with a first stop valve, a first viewing mirror, a CO2 mass flow meter, a mixing chamber, a first electronic expansion valve, a preheater and a CO2 trans-critical cycle heat exchange characteristic test section; the condenser is further sequentially connected with a fifth stop valve of a lubricating oil branch, a piston-type oil storage device, an adjustable valve of the lubricating oil branch, a high pressure oil pump, a second viewing mirror, a lubricating oil mass flow meter and a check valve, wherein the check valve is connected between the CO2 mass flow meter and a mixing chamber oil path; and the condenser is also sequentially connected with a rear heater, a second stop valve, a high-efficiency oil separator, a fourth stop valve in the lubricating oil branch, and the piston-type oil storage device. The device adopts an intermittent oil returning method so that the measurement of the lubricating oil mass flow is accurate.

Description

technical field [0001] The invention relates to a measuring device in the technical field of refrigeration and air conditioning, in particular to a CO 2 - Oil mixture transcritical cycle heat transfer measurement device. Background technique [0002] for CO 2 In the vapor compression refrigeration system, lubricating oil will inevitably be dissolved in the system, and these lubricating oils will affect CO 2 The heat transfer and pressure drop characteristics of the transcritical cycle have varying degrees of influence. Evaluation of lubricants against CO 2 The effect of transcritical cycle heat transfer on directing CO 2 Optimal design of air conditioner heat exchangers and evaluation of system characteristics are very important. [0003] In order to measure lubricating oil to CO 2 The effects of heat transfer in transcritical cycles require the transfer of CO 2 Lubricating oil is injected into the measuring circuit. In the prior art, two methods are used for injecti...

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Problems solved by technology

This method has many disadvantages: 1) Using off-line oil injection, every time the ratio of refrigerant and lubricating oil in the system is changed, oil must be manually injected into the system

2) The ratio adjustment of refrigerant and lubricating oil is discontinuous, and the ratio is not easy to control accurately

3) Since manual oil injection is required to change the ratio, when the oil concentration needs to change in a wide range, the workload of oil injection will be increased, the manpower and time consumption of the experiment will be increased, and the experimental efficiency will be reduced.

However, this method is not suitable for high operating pressure refrigerants such as CO 2 There are also some problems during oil injection and oil return: 1) Since the oil reservoir used in method two is a non-pressurizable oil reservoir, the internal pressure is very low (close to atmospheric pressure) during operation, and it is suitable for operating pressure lower than Oil injection of 3MPa refrigerant, while high operating pressure refrigerant such as CO 2 The pressure in the measurement circuit is as high as 7~12MPa, and the internal pressure of the oil reservoir is too low, which will make it impossible to inject lubricating oil into CO 2 Measuring circuit

2) High pressure CO 2 It has a high solubility in lubricating oil, and part of CO will be mixed into the lubricating oil entering the oil reservoir. 2 , the way of continuous oil return will make the oil reservoir to CO 2 What is injected into the measuring circuit is not pure lubricating oil but CO 2 Mixture with lubricating oil, resulting in unstable oil injection flow and inaccurate measurement

Therefore, although method 2 solves the problems of method 1, it is not suitable for refrigerants with high operating pressure such as CO due to its own limitations. 2 Measurement of heat transfer in transcritical cycle with oil mixture

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