CN110296623B

CN110296623B - Engine laboratory waste heat utilization method

Info

Publication number: CN110296623B
Application number: CN201910638847.5A
Authority: CN
Inventors: 吴昊; 华弢; 毛炜琦; 蔡军; 朱庆秋; 杨明; 王建宏; 蒋佳豪
Original assignee: FAW Jiefang Automotive Co Ltd
Current assignee: FAW Jiefang Automotive Co Ltd
Priority date: 2019-07-16
Filing date: 2019-07-16
Publication date: 2020-08-14
Anticipated expiration: 2039-07-16
Also published as: CN110296623A

Abstract

The invention discloses a method for utilizing waste heat of an engine test room, belonging to the engine test technology. Aiming at the problems that the existing circulating water system of a laboratory is lack of a waste heat utilization method and cannot recycle waste heat, the invention designs a set of waste heat recycling method by utilizing the existing circulating water system of the laboratory, realizes waste heat recycling by controlling hot water, cooling water and chilled water, and can self-regulate the system no matter how much waste heat is generated by a test object without influencing the test. The low waste heat cannot be recycled; the situation that the test cannot be normally carried out due to too high temperature because high waste heat cannot be absorbed in time and the measurement has deviation is avoided; the waste heat energy recycling process has no invalid energy or pollution energy, the system achieves the aim through physical heat exchange, and has no potential safety hazard, long service life and reliability.

Description

Engine laboratory waste heat utilization method

Technical Field

The invention belongs to the engine test technology.

Background

In the working process of the engine, the engine can generate a large amount of heat, and energy consumption can be reduced and pollution to the environment is reduced by recycling waste heat. The most of the currently published patents are used for the whole vehicle, and the method is summarized as follows: the heat of tail gas and other systems is collected through a heat exchange system, and the collected energy is converted into electric energy or mechanical energy through other energy conversion systems to be stored or directly used for other systems.

With the increasingly strict emission requirements of the nation for automobile engines, automobile engine enterprises have also begun to put higher test condition demands on engine laboratories. The test conditions of the traditional laboratory are generally simple and crude, and cannot meet strict test environment requirements and emission test conditions, so that the improvement of the test conditions and the test capacity of the laboratory is particularly important. In addition, the laboratory test capability is improved, and meanwhile, the energy conservation and the utilization rate improvement in response to national policies are also important considerations.

The publication number is CN106246268A comprehensive recovery system of engine waste heat. The comprehensive recovery system for the waste heat of the engine comprises a condenser, a single-screw expander, a generator, an exhaust gas discharge pipe of the engine, an evaporative heat exchanger and the like, wherein the high-grade energy recovery system of the engine is used for recovering the exhaust gas with high-grade energy, and the treated exhaust gas and the low-grade energy cooling water of the engine are jointly used as heat sources to drive a lithium bromide absorption type refrigerating machine so as to fully recover the heat of the exhaust gas. The scheme has high cost, long and complex pipelines need to be arranged, and auxiliary equipment needs to be purchased; pressure cannot be guaranteed when the pressure testing device is used for a plurality of tests, but if the pressure is increased, the pressure of partial parts can be overlarge to cause danger; the refrigerator is easy to leak air after long-term vacuum operation, thereby influencing the performance of the unit; lithium bromide has strong corrosive force on steel pipelines and influences the cold quantity of a unit; the cooling water of the refrigerator can generate crystallization at low temperature to influence the operation.

The publication number is CN107650622A 'an engine waste heat recycling system', an invention patent. The waste heat of gas entering the intercooler after the supercharger is recovered by the waste heat of cooling water of the engine and the heat exchange device of the waste heat of the inlet gas, and the waste heat of the gas is used for quickly warming a vehicle and heating an air conditioner. The utilization rate of the waste heat of the engine is improved. The scheme needs corresponding heat exchange devices for absorbing heat of equipment such as a supercharger, an exhaust gas post-treatment device and the like, but engines of different models and post-treatment systems in a test room cannot meet all models by one set of heat exchange device, and if the heat exchange device is designed and manufactured for each model, time, energy and cost are wasted; the system is too complex, the more pipeline controls the more energy losses recovered and the more additional energy consumed.

The publication number is CN109139289A comprehensive utilization system of engine waste heat. By utilizing the waste heat utilization technology of the engine body, the waste heat utilization technology of the exhaust pipe, the existing Stirling engine and other modes for comprehensive utilization, a new power source is formed, the consumption of fuel is reduced, and the purpose of energy conservation is achieved. The external combustion engine used in the scheme has larger volume, and the used matched equipment such as an expansion chamber, a compression chamber, a heating chamber, a cooling chamber, a regeneration chamber and the like has higher cost; the heat loss is large, and in addition, the problem of how much heat can be recovered due to the immature technical cost of each system exists; the stirling engine needs high temperature for operation, and waste heat recovery cannot necessarily provide such high temperature through heat exchange, so that the stirling engine cannot operate; even if the waste heat can reach the requirement, the generated electric energy of the external combustion engine is impure due to unstable supply, and the damage of the laboratory system equipment can be caused.

The above three patent applications have a common problem that the modification cost is too high; and secondly, the exhaust gas waste heat is recovered, but is absorbed, the measurement of the exhaust gas emission value is influenced by the temperature reduction, and the normal operation of the engine test cannot be influenced by the waste heat utilization.

Disclosure of Invention

The circulating water system of the existing test room mostly adopts air cooling heat dissipation through a cooling water tower, and each test room and each system are independent and unrelated, but the distributed control mode of the whole test room system established by the invention improves the energy utilization rate and the control precision by utilizing a unified control system, and simultaneously does not influence the independent operation of each test room.

At present, an engine waste heat recycling system is basically designed for an engine mounted on a vehicle, and cannot be used for waste heat utilization of an engine laboratory or due to extremely high cost or due to influences on measurement conditions and the like.

The invention provides a waste heat utilization method for an engine test room, which comprises the following steps:

firstly, judging a working mode:

1) the judgment is carried out according to the water temperature state,

2) after the temperature of hot water meets the requirement, if the boiler is started, entering a hot water mode, if the boiler is not started, judging whether to continue the hot water mode, and if so, entering the hot water mode; if not, returning to the step 1) again to judge according to whether the water temperature meets the requirement;

3) when the water temperature of the hot water does not meet the requirement, if the boiler is not started, entering a cold water mode; if the boiler is started, judging whether to continue the cold water mode, if so, entering the cold water mode; if not, returning to the step 1) again to judge according to whether the water temperature meets the requirement.

The temperature requirements for the cold water mode and the hot water mode are set according to the temperature required by the engine laboratory.

Secondly, the control steps in the hot water mode are as follows:

1) a difference between the heat exchange temperature set value and the temperature actual value is judged,

2) if the actual value is less than the set value, controlling to close the freezing water valve and the cooling water valve, and opening the PID control valve opening through the hot water valve to heat the circulating water;

3) if the actual value is larger than the set value, if the opening degree of the hot water valve is larger than 0%, the hot water valve is closed first, if the opening degree of the hot water valve is equal to 0%, the cooling water valve is opened, and the opening degree of the cooling water valve is adjusted through PID to cool the circulating water to the actual value which is equal to the set value;

4) when the opening of the cooling water valve reaches 100%, and the actual value is larger than the set value, the opening of the cooling water valve is adjusted to be constant to 80%, the freezing water valve is opened simultaneously, and the opening of the freezing water valve is adjusted through PID to reduce the temperature of the circulating water to the actual value which is the set value.

Secondly, the control steps in the cold water mode are as follows:

1) a difference between the actual value of the temperature of the heat exchange and the set value is judged,

2) if the actual value is less than or equal to the set value, closing the hot water valve, the cooling water valve and the freezing water valve to wait for the water temperature to rise;

3) if the actual value is larger than the set value and the opening degree of the hot water valve does not reach 100%, controlling the opening degree of the hot water valve through PID and adjusting the water temperature;

4) when the opening degree of the hot water valve reaches 100% and the actual value is larger than the set value, the opening degree of the hot water valve is adjusted to 80%, the cooling water valve is opened, and the opening degree of the cooling water valve is adjusted through PID to reduce the temperature of circulating water;

5) when the opening of the cooling water valve reaches 100% and the actual value is larger than the set value, the opening of the cooling water valve is adjusted to 80%, the chilled water valve is opened, and the opening of the chilled water valve is adjusted by the PID to reduce the temperature of the circulating water.

The invention has the beneficial effects that:

(1) the invention is suitable for recycling waste heat of the engine test room so as to achieve the effect of saving energy;

(2) the invention can be modified by using the original equipment of the test room (the test room is provided with a water cooling system and can be used), and the cost is low. Only need add the circulating water system of a test room when later stage need increase the laboratory can, need not additionally add equipment.

(3) The invention can not be inapplicable due to different test engines, and is even suitable for other test rooms using similar water circulation systems, and the universality is good;

(4) the system can be self-regulated no matter how much waste heat is generated by the test object, and the test is not influenced. The low waste heat cannot be recycled; the situation that the test cannot be normally carried out due to too high temperature because high waste heat cannot be absorbed in time and the measurement has deviation is avoided;

(5) the waste heat energy recycling process has no invalid energy or pollution energy, the system achieves the aim through physical heat exchange, and has no potential safety hazard, long service life and reliability.

Drawings

FIG. 1 is a schematic view of a hot water system

FIG. 2 is a schematic diagram of a circulating water system in a test room

FIG. 3 is a schematic view of a fresh air system

FIG. 4 is a flowchart of mode determination

FIG. 5 flow chart of hot water mode

FIG. 6 flow chart for cold water mode

Fig. 7 is a schematic diagram of waste heat utilization.

Detailed Description

The public water system pipeline of the laboratory consists of hot water, cooling water, chilled water and the like. Here, as represented by a hot water line, as shown in the figure (a), hot water is driven by a water pump, passes through a boiler, reaches a constant pressure tank, flows out at a constant pressure, and passes through other environmental systems and test rooms in sequence to form a circulation. Therefore, if the heat exchange system of a certain test room is used as a heat source, the water heating system can be directly used as hot water of other test rooms. Meanwhile, each system is relatively independent and can be independently opened or closed, so that the water temperature is influenced, but the use of other systems is not influenced. In the future, only one more branch is needed to be added in the laboratory, and the total pipeline is kept unchanged. The cooling water is basically similar to the chilled water pipeline, except that the boiler is replaced by an air cooling unit and a refrigerating unit.

The main pipeline of the circulating water system in the test room is shown in figure 2 and is divided into 1 cooling water heat exchange module; 2, a chilled water heat exchange module; 3. a hot water heat exchange module; 4. and the test room heat exchange module. Wherein each heat exchange module is realized by a plate heat exchanger, and each water system is physically isolated. The circulating water is driven by a water pump to keep pressure through a pressure stabilizing tank, then sequentially passes through a cooling water heat exchange plate, a chilled water heat exchange plate and a hot water heat exchange plate to reach a set temperature and then reaches a heat exchange plate of a test room, and the temperature of cooling water in the test room is controlled through the opening degree of a proportional valve. The circulating water temperature of each test room can be set independently and is not influenced by other test rooms.

As shown in figure 3, the fresh air is sent to each test room or preparation room after reaching a set temperature through double heat exchange of hot water and cold water, the temperature of the fresh air is controlled by the opening degrees of hot water and cold water valves, and the hot water and the cold water passing through the heat exchange plates come from a hot water system and a chilled water system, so that the heat energy of the water system can be fully utilized. The system can simulate the influence of different environmental temperatures on combustion emission when the whole vehicle runs by matching with an indoor fan.

The above is the hardware facility arrangement of the invention, and in order to realize the accurate control of the test condition system and the recycling of the engine waste heat, the invention also needs to develop the relevant software for real-time control, which is the essence of the invention. The specific software operating system may be different as long as the control logic is satisfied, so that the detailed description is omitted here, and only the most core relevant control logic is described. (the control logic of FIGS. 4 to 6 below is primarily applied to the test room circulating water system shown in FIG. 2)

The first step of the control logic is judged as shown in the figure (four), and the working mode is judged as follows:

1) the judgment is carried out according to the water temperature state,

Secondly, the control steps in the hot water mode are as follows (as shown in fig. 5):

Secondly, the control steps in the cold water mode are as follows (as shown in fig. 6):

The waste heat recovery and utilization are shown in fig. 7. At present, engine tests have requirements on the temperature of circulating water and the environmental temperature of a test room. For the test room, the "cold water mode" shown in fig. 6 is waste heat absorption, and the "hot water mode" shown in fig. 5 is waste heat utilization. After the test room is started and absorbs waste heat in a cold water mode, the test room which is started later can be warmed up in a hot water mode, so that the circulating water reaches the set temperature as soon as possible, and the preparation time is saved; the fresh air system is equivalent to an air conditioner in a test room, can adjust the indoor temperature and cooperate with an indoor circulating fan to quickly enable the environmental temperature to reach the standard, and meanwhile, the fresh air system can be used as the air conditioner in a preparation room in winter, and the hot water heat exchange plate is used for heating the preparation room, so that the energy is saved; other systems needing hot water are added according to the needs of a laboratory, only one branch and one heat exchange plate are needed to be added, and both water heat exchange and wind heat exchange are convenient.

Claims

1. A waste heat utilization method for an engine test room comprises the following steps:

firstly, judging a working mode:

1) the judgment is carried out according to the water temperature state,

3) when the water temperature of the hot water does not meet the requirement, if the boiler is not started, entering a cold water mode; if the boiler is started, judging whether to continue the cold water mode, if so, entering the cold water mode; if not, returning to the step 1) again to judge according to whether the water temperature meets the requirement;

the temperature requirements of the cold water mode and the hot water mode are set according to the temperature required by an engine laboratory;

secondly, the control steps in the hot water mode are as follows:

4) when the opening of the cooling water valve reaches 100%, and the actual value is larger than the set value, the opening of the cooling water valve is adjusted to be constant to 80%, and meanwhile, the freezing water valve is opened, and the opening of the freezing water valve is adjusted through PID (proportion integration differentiation) to reduce the temperature of circulating water to the actual value which is equal to the set value;

secondly, the control steps in the cold water mode are as follows: