阅读说明：本技术 基于二氧化碳动力循环的柴油机余热利用梯级耦合系统 (Diesel engine waste heat utilization cascade coupling system based on carbon dioxide power circulation ) 是由 田华 李力耕 舒歌群 石凌峰 于 2019-11-25 设计创作，主要内容包括：本发明公开了一种基于二氧化碳动力循环的柴油机余热利用梯级耦合系统,包括：工质泵、缸套冷却水换热器、增压中冷换热器、中间换热器、烟气换热器、EGR中冷换热器、膨胀发电一体机、储液罐以及冷凝器。在根据本发明所述的适用于柴油机余热利用的梯级耦合系统中,采用跨临界或超临界二氧化碳动力循环,通过设置不同的换热器,基于按质用能和温度匹配理论将柴油机各梯级余热予以高效回收,已达到提高柴油机效率、降低燃油消耗量的目的。(The invention discloses a diesel engine waste heat utilization cascade coupling system based on carbon dioxide power circulation, which comprises: the system comprises a working medium pump, a cylinder sleeve cooling water heat exchanger, a supercharging intercooling heat exchanger, an intermediate heat exchanger, a flue gas heat exchanger, an EGR intercooling heat exchanger, an expansion and power generation integrated machine, a liquid storage tank and a condenser. In the cascade coupling system suitable for waste heat utilization of the diesel engine, the aim of improving the efficiency of the diesel engine and reducing the fuel consumption is fulfilled by adopting transcritical or supercritical carbon dioxide power circulation and efficiently recovering waste heat of each cascade of the diesel engine based on the mass energy and temperature matching theory by arranging different heat exchangers.)

1. The cascade coupling system for utilizing the waste heat of the diesel engine based on carbon dioxide power circulation is characterized by comprising a working medium pump (1), wherein an outlet of the working medium pump (1) is divided into a first branch and a second branch, the first branch is connected with a tube side inlet of a cylinder sleeve cooling water heat exchanger (2), and cylinder sleeve cooling water of the diesel engine (10) is introduced into a shell side of the cylinder sleeve cooling water heat exchanger (2); the second branch is connected with a tube side inlet of the supercharging intercooling heat exchanger (3), and the supercharging air of the diesel engine (10) is introduced into the shell side of the supercharging intercooling heat exchanger (3); a tube side outlet of the cylinder jacket cooling water heat exchanger (2) and a tube side outlet of the supercharging intercooling heat exchanger (3) are converged and then connected with a cold side runner inlet of the intermediate heat exchanger (4), the cold side runner outlet of the intermediate heat exchanger (4) is divided into a third branch and a fourth branch, the third branch is connected with the tube side inlet of the flue gas heat exchanger (6), and exhaust of the diesel engine (10) is introduced into a shell side of the flue gas heat exchanger (6); the fourth branch is internally connected with a tube side inlet of an EGR intercooling heat exchanger (5), and exhaust gas of the diesel engine (10) is introduced into a shell side of the EGR intercooling heat exchanger (5); and a tube pass outlet of the flue gas heat exchanger (6) and a tube pass outlet of the EGR intercooling heat exchanger (5) are converged and then sequentially connected with an expansion and power generation all-in-one machine (7), a hot side runner of the intermediate heat exchanger (4), a condenser (8) and an inlet of a liquid storage tank (9), and an outlet of the liquid storage tank (9) is connected to an inlet of the working medium pump (1).

2. The carbon dioxide power cycle-based diesel engine waste heat utilization cascade coupling system as claimed in claim 1, wherein an outlet of the working medium pump (1) is divided into the first branch and the second branch by a first flow dividing valve (a).

3. The carbon dioxide power cycle-based diesel engine waste heat utilization cascade coupling system is characterized in that a tube pass outlet of the cylinder jacket cooling water heat exchanger (2) and a tube pass outlet of the supercharging intercooling heat exchanger (3) are merged through a first merging valve (B).

4. The carbon dioxide power cycle-based diesel engine waste heat utilization cascade coupling system is characterized in that a cold side runner outlet of the intermediate heat exchanger (4) is divided into the third branch and the fourth branch through a second flow dividing valve (C).

5. The diesel engine waste heat utilization cascade coupling system based on carbon dioxide power cycle as claimed in claim 1, wherein the tube side outlet of the flue gas heat exchanger (6) and the tube side outlet of the EGR inter-cooler heat exchanger (5) are merged through a second merging valve (D).

Technical Field

The invention relates to a diesel engine waste heat utilization technology, in particular to a cascade coupling system based on carbon dioxide power circulation and suitable for diesel engine waste heat utilization.

Background

Energy conservation and emission reduction become one of the targets pursued by main power devices at home and abroad, and the utilization of waste heat of the diesel engine is acknowledged as the most potential energy-saving measure. From the energy balance of the existing diesel engine, the power output power only accounts for 30% -45% of the total heat of fuel combustion (diesel engine), and the rest over 60% of the residual heat energy is not utilized, but is dissipated to the atmosphere through heat dissipation, exhaust and other forms of a cooling loop. Therefore, recycling the waste heat energy of the diesel engine is an effective way for improving the total energy efficiency and reducing the oil consumption.

CO utilizing waste heat of existing diesel engine₂Power cycle system has the characteristics that can high-efficiently retrieve cylinder liner cooling water and diesel engine tail gas energy simultaneously, and the structure is comparatively simple, possesses miniaturized and lightweight advantage, has received extensive attention and research in the aspect of the waste heat energy utilization. However, because the temperature characteristics of the waste heat source of the diesel engine have the characteristics of large temperature gradient, large taste difference and the like, the efficiency of the existing system is not high, the heat source is not fully utilized, the output power of the system is lower than that of an organic working medium, and the working capacity and the practical application of the system are restricted.

In view of the above background and the current technical situation, if the system work capacity can be further improved and the waste heat sources of the diesel engines can be reasonably and fully utilized, the energy saving and consumption reduction effects on the diesel engines can be achieved. Therefore, the invention provides a cascade coupling system based on carbon dioxide power circulation and suitable for waste heat energy utilization of a diesel engine, so as to improve the system working capacity and achieve the aims of energy conservation and emission reduction of the diesel engine.

Disclosure of Invention

In view of the problems in the prior art, the invention aims to provide a cascade coupling carbon dioxide power cycle system suitable for diesel engine waste heat utilization, which can reasonably utilize the diesel engine waste heat of different temperature regions with different tastes so as to improve the net power output and the heat efficiency of a diesel engine and further achieve the purpose of improving the fuel economy of the diesel engine.

The technical scheme adopted by the invention is as follows: a diesel engine waste heat utilization cascade coupling system based on carbon dioxide power circulation comprises a working medium pump, wherein an outlet of the working medium pump is divided into a first branch and a second branch, the first branch is connected with a tube side inlet of a cylinder jacket cooling water heat exchanger, and cylinder jacket cooling water of a diesel engine is introduced into a shell side of the cylinder jacket cooling water heat exchanger; the second branch is connected with a tube side inlet of a supercharging intercooling heat exchanger, and supercharging air of the diesel engine is introduced into a shell side of the supercharging intercooling heat exchanger; the tube side outlet of the cylinder jacket cooling water heat exchanger and the tube side outlet of the supercharging intercooling heat exchanger are converged and then connected with the cold side runner inlet of the intermediate heat exchanger, the cold side runner outlet of the intermediate heat exchanger is divided into a third branch and a fourth branch, the third branch is connected with the tube side inlet of the flue gas heat exchanger, and exhaust of the diesel engine is introduced into the shell side of the flue gas heat exchanger; the fourth branch is internally connected with a tube side inlet of an EGR intercooling heat exchanger, and exhaust gas of the diesel engine is introduced into a shell side of the EGR intercooling heat exchanger; and a tube pass outlet of the flue gas heat exchanger and a tube pass outlet of the EGR intercooling heat exchanger are converged and then sequentially connected with the expansion and power generation integrated machine, a hot side flow channel of the intermediate heat exchanger, the condenser and an inlet of the liquid storage tank, and an outlet of the liquid storage tank is connected to an inlet of the working medium pump.

Further, an outlet of the working medium pump is divided into the first branch and the second branch through a first flow dividing valve.

Further, a tube pass outlet of the cylinder jacket cooling water heat exchanger and a tube pass outlet of the supercharging intercooling heat exchanger are converged through a first confluence valve.

Further, a cold side runner outlet of the intermediate heat exchanger is divided into the third branch and the fourth branch by a second flow dividing valve.

Further, a tube side outlet of the flue gas heat exchanger and a tube side outlet of the EGR inter-cooling heat exchanger are converged through a second confluence valve.

The invention has the beneficial effects that: the invention is based on the principle of matching energy according to quality and temperature, and the heat exchangers from the low-temperature area to the high-temperature area are reasonably arranged, so that the main waste heat and heat sources of the diesel engine are comprehensively utilized, the heat absorption capacity of the system is improved, and the system is further improvedUnified working medium CO₂The mass flow of the diesel engine further increases the work capacity of the system, the system performance is improved through the novel design of twice shunting and twice converging, and the waste heat with multiple tastes and large temperature gradient of the diesel engine is better absorbed to achieve the purpose of energy conservation.

Drawings

FIG. 1: the invention discloses a schematic diagram of a diesel engine waste heat utilization cascade coupling system based on carbon dioxide power circulation.

The attached drawings are marked as follows: 1. a working medium pump; 2. a cylinder jacket cooling water heat exchanger; 3. a pressurized intercooling heat exchanger; 4. an intermediate heat exchanger; 5. EGR intercooling heat exchanger; 6. a flue gas heat exchanger; 7. an expansion power generation integrated machine; 8. a condenser; 9. a liquid storage tank; 10. a diesel engine;

A. a first diverter valve; B. a first confluence valve; C. a second diverter valve; D. a second confluence valve;

wherein the thick solid line represents CO₂Power circulation; the dashed line indicates the diesel engine cylinder liner cooling water circulation path; the double thin solid lines represent the diesel charge air intercooling circulation path; the long dashed line represents the cold circulation path in diesel Exhaust Gas Recirculation (EGR); the double dashed line represents the diesel exhaust path.

Detailed Description

In order to further understand the contents, features and effects of the present invention, the following embodiments are illustrated and described in detail with reference to the accompanying drawings:

as shown in the attached drawing 1, the diesel engine waste heat utilization cascade coupling system based on carbon dioxide power circulation comprises a working medium pump 1, a cylinder sleeve cooling water heat exchanger 2, a supercharging intercooling heat exchanger 3, an intermediate heat exchanger 4, an EGR intercooling heat exchanger 5, a flue gas heat exchanger 6, an expansion and power generation integrated machine 7, a liquid storage tank 9, a condenser 8, a diesel engine 10, a first flow dividing valve A, a second flow dividing valve C, a first flow merging valve B, a second flow merging valve D and the like.

An outlet of the working medium pump 1 is divided into a first branch and a second branch through a first flow divider A, the first branch is connected with a tube pass inlet of the cylinder jacket cooling water heat exchanger 2, and cylinder jacket cooling water of the diesel engine 10 is introduced into a shell pass of the cylinder jacket cooling water heat exchanger 2; the second branch is connected with a tube side inlet of the charge intercooling heat exchanger 3, and charge air of the diesel engine 10 is introduced into a shell side of the charge intercooling heat exchanger 3. The tube side outlet of the cylinder jacket cooling water heat exchanger 2 and the tube side outlet of the supercharging intercooling heat exchanger 3 are converged by a first confluence valve B and then are connected with the cold side runner inlet of the intermediate heat exchanger 4, the cold side runner outlet of the intermediate heat exchanger 4 is divided into a third branch and a fourth branch by a second diversion valve C, the third branch is connected with the tube side inlet of the flue gas heat exchanger 6, and the exhaust gas of the diesel engine 10 is introduced into the shell side of the flue gas heat exchanger 6; the fourth branch is internally connected with a tube side inlet of the EGR inter-cooling heat exchanger 5, and the recirculating exhaust gas of the diesel engine 10 is introduced into a shell side of the EGR inter-cooling heat exchanger 5. And a tube pass outlet of the flue gas heat exchanger 6 and a tube pass outlet of the EGR intercooling heat exchanger 5 are converged by a second converging valve D and then sequentially connected with the expansion and power generation all-in-one machine 7, a hot side flow passage of the intermediate heat exchanger 4, the condenser 8 and an inlet of the liquid storage tank 9, and an outlet of the liquid storage tank 9 is connected to an inlet of the working medium pump 1.

The invention comprehensively examines the main waste heat source of the diesel engine, and fully utilizes the main waste heat source according to the temperature characteristics of different heat sources based on the principle of matching energy according to quality and temperature, and the working process comprises the following steps: working medium CO in system₂After being pressurized by the working medium pump 1, the high-pressure low-temperature fluid is formed; then the working fluid is divided into two paths by the design of a first flow dividing valve A, wherein one path of working fluid CO is divided into two paths₂Enters the cylinder jacket cooling water heat exchanger 2, and heats working medium CO in the cylinder jacket water heat exchanger by using the cylinder jacket water heat quantity of the diesel engine 10₂The working medium CO₂Absorbing the waste heat of cylinder liner water of the diesel engine 10 to become high-pressure fluid with higher temperature; another stream of working medium CO₂Then enters the supercharging inter-cooling heat exchanger 3, and the inter-cooling energy of the supercharged air of the diesel engine 10 is utilized to heat the working medium CO in the supercharging inter-cooling heat exchanger 3₂Absorbing heat of cold in the supercharged air of the diesel engine 10; two streams of working substances CO₂After being converged by the first flow-converging valve B, the mixture uniformly enters the intermediate heat exchanger 4 and is processed by working medium CO₂Further heating the expanded exhaust steam heat; working fluid CO₂Performing secondary flow division, passing through a second flow dividing valve C, whereinOne strand of working medium CO₂Flows into the flue gas heat exchanger 6, and heats working medium CO in the flue gas heat exchanger 6 by high-temperature exhaust gas of the diesel engine 10₂Absorbing the exhaust heat of the diesel engine 10; another stream of working medium CO₂Then the exhaust gas enters the EGR inter-cooling heat exchanger 5, and the inter-cooling heat quantity of the exhaust gas recirculation of the diesel engine 10 is utilized to cool the working medium CO in the EGR inter-cooling heat exchanger 5₂Heating to absorb the cold heat in the exhaust gas recirculation of the diesel engine 10; two streams of working substances CO₂After the second confluence valve D carries out secondary confluence, high-temperature high-pressure supercritical CO is formed₂Working medium, high-temperature high-pressure supercritical CO₂The working medium is introduced into the expansion and power generation integrated machine 7 to do expansion work and push the generator to generate power; high-temperature high-pressure supercritical CO after work doing₂Still has certain energy, so the heat exchange medium is led into the intermediate heat exchanger 4 to complete internal heat exchange, further the cold measuring working medium is heated by utilizing the heat of the heat exchange medium, and then the cold measuring working medium flows into the condenser 8 to be condensed to become CO with low temperature and low pressure₂The fluid has the work-doing capability again, and finally flows back to the liquid storage tank 9 to complete the whole CO₂And is circulated and returned to working fluid pump 1 to complete the next cycle, as shown by the thick solid line in fig. 1. For a cylinder liner water heat exchanger, a dashed line in fig. 1 shows a cylinder liner cooling water circulation path of a diesel engine 10; for the charge intercooling heat exchanger 3, the thin double-solid line part in fig. 1 represents the charge air intercooling circulation path of the diesel engine 10; for the EGR intercooler 5, the dashed-long line part in fig. 1 represents the EGR circulation path of the diesel engine 10; for the flue gas heat exchanger 6, the double dashed line in fig. 1 indicates the exhaust path of the diesel engine 10.

The cylinder jacket cooling water heat exchanger 2 and the supercharging intercooling heat exchanger 3 realize the primary heating function of the working medium, namely the utilization of the cylinder jacket cooling water waste heat and the supercharging intercooling waste heat is completed; the intermediate heat exchanger 4 realizes the heating function of the expanded high-temperature low-pressure working medium on the low-temperature high-pressure working medium, namely, the recycling of the heat in the system is completed; the EGR intercooling heat exchanger 5 and the flue gas heat exchanger 6 realize the utilization of the exhaust gas recirculation intercooling waste heat and the tail gas heat of the diesel engine 10.

The first flow dividing valve A, the second flow dividing valve C, the first flow converging valve B and the second flow converging valve D achieve the purpose of system flow dividing and converging, and meanwhile, the mass flow of the working medium is reasonably distributed and adjusted and controlled.

The expansion power generation integrated machine 7 can be realized by CO₂The conversion of the internal energy of the working medium to the kinetic energy is efficiently completed by the generator.

Cooling water paths are arranged around the liquid storage tank 9 to ensure that CO entering the liquid storage tank 9₂Has been completely cooled to a saturated liquid state.

CO₂The system circulation working medium is suitable for transcritical circulation and supercritical circulation.

The invention realizes the cascade utilization of all waste heat of the diesel engine and fully absorbs the waste heat of each diesel engine through the novel design of primary shunting and secondary shunting based on the theory of matching according to the quality and energy and the temperature, so that the system optimizes the utilization of waste heat source energy, overcomes the defects of low efficiency and poor function of a non-shunting system, improves the efficiency of the diesel engine, reduces the fuel consumption and has great significance for reducing the emission of diesel engines.

The circulating system is suitable for transcritical or supercritical CO₂Recycling, using transcritical or supercritical CO₂As power circulation, through arranging different heat exchangers, through reasonable temperature matching from low to high and flow adjustment control of shunting, the waste heat of each step of the diesel engine is efficiently recovered, the full utilization of the waste heat in the range with multiple tastes and large temperature gradients of the diesel engine is realized to the maximum extent, and the purposes of saving energy of the diesel engine and improving the work capacity of the system are achieved.

Although the preferred embodiments of the present invention have been described above with reference to the accompanying drawings, the present invention is not limited to the above-described embodiments, which are merely illustrative and not restrictive, and those skilled in the art can make many modifications without departing from the spirit and scope of the present invention as defined in the appended claims.