CN104610919A

CN104610919A - Environment-friendly refrigerant suitable for low-temperature freezing system

Info

Publication number: CN104610919A
Application number: CN201510096020.8A
Authority: CN
Inventors: 杨昭; 赵松松; 田田; 陈爱强; 张娜; 陈明锋
Original assignee: Tianjin University
Current assignee: Tianjin University
Priority date: 2015-03-04
Filing date: 2015-03-04
Publication date: 2015-05-13
Anticipated expiration: 2035-03-04
Also published as: CN104610919B

Abstract

The invention discloses an environment-friendly refrigerant suitable for a low-temperature freezing system. The refrigerant comprises the following components in percentage by mass: 50 percent of difluoromethane, 3 percent of dimethyl ether and 47 percent of 1,1,1,2-tetrafluoroethane. When a condensing temperature is 25 to 30 DEG C and an evaporating temperature is about minus 25 DEG C, relative COPs (Coefficient Of Performance) are 1.020(40HZ) and 1.035(50Hz) and an energy-saving rate of the system is over 5 percent. The environment-friendly refrigerant suitable for the low-temperature freezing system replaces an R404A high-efficiency environment-friendly refrigerant, has the characteristics of ODP (ozone depleting potential) of zero, low GWP (Global Warming Potential) (946), small charge (about 70 percent), excellent thermodynamic property, excellent market availability and the like and can be directly charged into an original freezing and cold storage system using the R404A refrigerant without replacing more parts or even refilling lubricating oil. Moreover, compared with the R404A refrigerant, the environmental-friendly refrigerant has better performance coefficient and energy-saving effect under the working conditions of the high condensing temperature and the low evaporating temperature.

Description

Be applicable to the environmental protection refrigerant of cryogenic refrigeration systems

Technical field

The invention belongs to the refrigeration agent in heat pump or refrigeration, air-conditioning system, be particularly useful for the environmental protection refrigerant of cryogenic refrigeration systems.

Background technology

In the frame foundation of Kyoto Protocol and Montreal protocol; national governments and scientific research institution and industry and enterprise have carried out a large amount of work from policy making, technical study to industrial practice; the up-to-date motion of fluoro-gas regulation in Europe proposes; the freezing and refrigeration cabinet of retail trade; from 2015; the GWP value of refrigeration agent must not more than 2150; more and more focus on from Ozonosphere protection in the world and suppressed global warming two broad aspect comprehensive evaluation refrigeration agent environmental-protecting performance, having reduced the important of GWP value as seen.By the end of the end of the year 2012, China will have about 9.85 ten thousand, freezer, increase by 11.3% on a year-on-year basis, wherein newly-increased cold storage capacity about 2,600,000 tons.According to " product Cold Chain Logistics development program " that National Development and Reform Commission announces, China plans national freezer total volume to be increased to 1,880 ten thousand tons in 2015, face the continuous growth of freezer quantity, demand and the production of refrigeration agent also day by day increase, and the superseded process accelerating high GWP value refrigeration agent is significant.

The most widely used R404A of current Refrigeration industry, belong to the refrigeration agent of the fluoro-gas regulation limitations in Europe, the research of its substitute technology is particularly urgent.R404A is a kind of ternary near-azeotrope mixture refrigerant, is the preferred alternative refrigerant of R502.But R404A remains in certain defect, although ODP value is 0, but still there is higher GWP (3850) value, incompatible with the environmental requirement of current control greenhouse gas emission.The present invention proposes a kind of non-azeotrope ternary mixed refrigerant and is applicable to cryogenic refrigeration systems, as the surrogate of R404A.

Summary of the invention

The object of this invention is to provide a kind of environmental protection refrigerant being applicable to cryogenic refrigeration systems; Substitute the mixed refrigerant of cryogenic freezing reefer system R404A, make its environmental characteristics and cycle performance the best.

The energy-saving and environmental-friendly refrigeration agent being applicable to cryogenic freezing reefer system of the present invention, is made up of R-32 (methylene fluoride), DME (dme) and R-134a (HFA 134a).

As shown in Table 1, it all has higher critical temperature and emergent pressure to the basic physical properties of three kinds of constituent elements, can use under worst hot case, it is relatively low that the ODP of three kinds of constituent elements is 0, GWP, especially DME, its GWP close to 0, and has higher refrigerating effect per unit swept volume.Although these three kinds of constituent elements have been proved and have been applicable to moderate and high temperature heat system in " moderate and high temperature heat working medium " patent, and there is good effect, but the operating mode of its High Temperature High Pressure can not carry out freezing and refrigerating system being directly applied for cryogenic refrigeration systems under too much change prerequisite, this patent carries out theoretical analysis to mix refrigerant under three kinds of constituent element different ratio, draw the refrigeration agent that physical parameter and R404A are very close, and there is the best composition ratio of relative higher COP, the direct punching that can realize novel refrigerant is filled with.The feature of novel energy-saving environment-friendly refrigeration agent is the concrete mass percent proportioning of three constituent element materials:

Methylene fluoride 50%,

Dme 3%,

HFA 134a 47%.

The each constituent element basic parameter of table 1 mixed refrigerant

Tb: normal boiling point, Tc: critical temperature, Pc: emergent pressure

The preparation method of environmental protection refrigerant of the present invention is, the quality proportioning cryogenic liquid (gas at normal temperature) that three constituent element materials are specified by it is carried out physical mixed.

About the physical parameter of mixed refrigerant and R404A is as shown in table 2: both physical parameters are basically identical, R404A is a kind of near azeotropic mixed refrigerant, at normal atmospheric pressure, the temperature glide of mixed refrigerant is 7.56 DEG C, mix refrigerant as non-azeotrope has reduction system pressure ratio, increase refrigerating duty, improve the advantages such as circulation thermodynamic perfect degree.Mixed refrigerant molecular weight comparatively R404A is low.Its GWP value is 946, is about 24.6% of R404A, and therefore the potential ability of Greenhouse effect is relatively little.

Although DME has inflammable and explosive characteristic, but the content in mixed refrigerant is less, and R-134a just has certain flame retardant resistance, therefore the combustibility of mixed refrigerant is greatly reduced, in addition DME is a kind of gas with special odor, can be used as a kind of method whether checking system is revealed.

Table 2 R404A compares with mixed refrigerant basic physical properties parameter

Parameter	R404A	Mixed refrigerant
			Molecular weight/(kg/kmol)	97.60	67.26
Critical temperature/DEG C	72.14	89.36
			Emergent pressure/kPa	3.375	5.254
Critical density/(kg/m3)	488.5	430.65
			Bubble point temperature (DEG C)	-46.57	-45.68
Dew-point temperature (DEG C)	-45.79	-38.12
			Temperature glide (DEG C)	0.78	7.56
ODP value/1	0	0
			GWP value/1	3850	946
Flammable	Do not fire	Weak combustibility

Note: temperature of saturation when bubble point temperature and dew-point temperature are standard atmospheric pressure 101kPa in table

Accompanying drawing explanation

Fig. 1 novel refrigerant compares with R404A refrigerating effect per unit swept volume;

Fig. 2 novel refrigerant compares with the COP of R404A;

Fig. 3 R404A exhaust temperature;

Fig. 4 novel refrigerant exhaust temperature.

Embodiment

Embodiment: according to mass percent be according to three constituent element materials

Methylene fluoride 50%,

Dme 3%,

HFA 134a 47%.

Carry out proportioning, carry out physical mixed with the state of low temperature liquid or normal temperature gaseous state and prepare refrigeration agent of the present invention.

Theoretical analysis and test is carried out to verify its beneficial effect below by substituting R404A to mixed refrigerant under different operating mode.The design conditions of freezing and refrigerating system are taken as: condensing temperature=10,15,20,25,30,35,40,45,50 DEG C; Vaporization temperature=0 ,-5 ,-10 ,-15 ,-20 ,-25,30 DEG C; Superheating temperature=25 DEG C (effectively overheated 5 DEG C, invalid overheated 20 DEG C); Condensate depression=5 DEG C; Compressor heat insulating ability 0.8, volumetric efficiency 0.95.

Respectively Theoretical Calculation is carried out to the refrigeration cycle performance parameter of mixed refrigerant and R404A under the different operating mode of freezing and refrigerating system, comprise refrigerating effect per unit swept volume, compressor exhaust temperature and condensing pressure etc., and compare of analysis has been carried out, as shown in accompanying drawing 1-4 to the relative performance parameter of the two.

Result shows: although the application of mixed refrigerant makes the exhaust temperature of compressor generally improve, but under the higher operating mode of condensing temperature its refrigerating effect per unit swept volume and coefficient of performance of refrigerating comparatively R404A increase, and larger along with its relative COP of reduction of vaporization temperature, illustrate that new refrigerant has energy-efficient advantage under certain operating mode.In view of the condensing pressure of the two is basically identical, this demonstrates the feasibility adopting direct filling type replacement scheme from system pressure angle.

Mixed refrigerant has that ODP is zero, the GWP feature such as excellent and market availability is good compared with low (946), charging amount few (about 70%), thermomechanical property, directly can fill and use in the freezing and refrigerating system of R404A refrigeration agent in original, do not need to do too much part replacement, more do not need re-injection lubricating oil.This patent is for enhancing China's freezing and refrigerating system refrigerant special competitive power in the international market, and the superseded process accelerating high GWP refrigeration agent is significant.

In higher condensing temperature (>35 DEG C), under lower vaporization temperature (<-30 DEG C) operating mode, mixed refrigerant has relatively high refrigerating effect per unit swept volume and COP relative to R404A, is a kind of energy-efficient refrigeration agent.

For preferred forms, freezing and refrigeration testing table tests actual working characteristics.Respectively under compressor unit 40Hz and 50Hz winter operation operating mode, the experimental study of refrigeration performance is carried out to the freezing and refrigerating system based on refrigeration agent R404A and mixed refrigerant.Cooling condition performance test results shows: this freezing and refrigerating system applies novel energy-saving environment-friendly refrigeration agent of the present invention can obtain the higher coefficient of performance, lower compressor high-low pressure ratio, less energy consumption.Be 25 ~ 30 DEG C in condensing temperature, during vaporization temperature about-25 DEG C, relative COP is 1.020 (40HZ), and 1.035 (50Hz), overall system fractional energy savings is all more than 5%.

Substitute the high-efficiency environment friendly refrigeration agent of R404A, have that ODP is zero, GWP lower (946), filling quantity less (about 70%), thermomechanical property are excellent and the feature such as market availability is good, directly can fill and use in the freezing and refrigerating system of R404A refrigeration agent in original, do not need to do too much part replacement, more do not need re-injection lubricating oil.And at higher condensing temperature R404A compared with under lower vaporization temperature operating mode, there is better properties coefficient and energy-saving effect.The present invention has extraordinary effect and development potentiality.

Claims

1. one kind is applicable to the environmental protection refrigerant of cryogenic refrigeration systems; It is characterized in that component and mass percent are:

Methylene fluoride 50%,

Dme 3%,

HFA 134a 47%.