Performance of a scroll compressor with vapor-injection and two-stage reciprocating compressor operating under extreme conditions

In order to understand the vapor injection flow characteristics of two-stage rotary compressor in the course of compression, a mathematical model based on mass conservation equation, energy equation and thermodynamic identity was established and proved by P-V diagram testing results. Some useful conclusions about pressure in the intermediate chamber and mass flow of vapor injection in the course of compression were also given out. The results show that, gas backflow between the intermediate chamber and the vapor injection channel is an important defection of two-stage rotary compressor which can be solved by the application of injection valve in vapor injection channel. The injection valve can obviously reduce the gas backflow and the power loss in the course of compression while increasing the pressure fluctuation in the intermediate chamber. Experiments show that the COP of two-stage rotary compressor with the injection valve increased by over 2% in ASHRAE/T working condition.

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Leakage Flow-Induced Vibrations of Heat Exchanger Fins

Journal of Pressure Vessel Technology ◽

10.1115/1.2929254 ◽

1992 ◽

Vol 114 (4) ◽

pp. 453-458

Author(s):

D. S. Weaver ◽

X. Y. Huang

Keyword(s):

Heat Exchanger ◽

Shear Layer ◽

Fatigue Failure ◽

Laboratory Tests ◽

Leakage Flow ◽

Reciprocating Compressor ◽

Excitation Mechanism ◽

Two Stage ◽

Flow Induced Vibrations

The failure of a number of fins of a large two-stage reciprocating compressor intercooler was studied. It appeared that leakage flow across the ends of the fins excited the vibrations and eventually led to fatigue failure. A series of simple laboratory tests were conducted to confirm this excitation mechanism. It is seen that the fins may be excited to resonance by coupling with the shear layer oscillations in several ways. The heat exchanger problem was cured by using sealing strips to prevent the leakage flow.

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A Low-Order HCCI Model Extended to Capture SI-HCCI Mode Transition Data With Two-Stage Cam Switching

Volume 2: Dynamic Modeling and Diagnostics in Biomedical Systems; Dynamics and Control of Wind Energy Systems; Vehicle Energy Management Optimization; Energy Storage, Optimization; Transportation and Grid Applications; Estimation and Identification Methods, Tracking, Detection, Alternative Propulsion Systems; Ground and Space Vehicle Dynamics; Intelligent Transportation Systems and Control; Energy Harvesting; Modeling and Control for Thermo-Fluid Applications, IC Engines, Manufacturing ◽

10.1115/dscc2014-6275 ◽

2014 ◽

Cited By ~ 1

Author(s):

Patrick Gorzelic ◽

Prasad Shingne ◽

Jason Martz ◽

Anna Stefanopoulou ◽

Jeff Sterniak ◽

...

Keyword(s):

Steady State ◽

Extreme Conditions ◽

Mode Transition ◽

Two Stage ◽

Model Based Control ◽

Model Based ◽

Hcci Combustion ◽

Transition Strategies ◽

Mode Transitions ◽

Low Order

A low-order homogeneous charge compression ignition (HCCI) combustion model to support model-based control development for spark ignition (SI)/HCCI mode transitions is presented. Emphasis is placed on mode transition strategies wherein SI combustion is abruptly switched to recompression HCCI combustion through a change of the cam lift and opening of the throttle, as is often employed in studies utilizing two-stage cam switching devices. The model is parameterized to a steady-state dataset which considers throttled operation and significant air-fuel ratio variation, which are pertinent conditions to two-stage cam switching mode transition strategies. Inspection and simulation of transient SI to HCCI (SI-HCCI) mode transition data shows that the extreme conditions present when switching from SI to HCCI can cause significant prediction error in the combustion performance outputs even with the model’s adequate steady-state fit. When a correction factor related to residual gas temperature is introduced to account for these extreme conditions, it is shown that the model reproduces transient performance output time histories in SI-HCCI mode transition data. The model is thus able to capture steady-state data as well as transient SI-HCCI mode transition data while maintaining a low-order cycle to cycle structure, making it tractable for model-based control of SI-HCCI mode transitions.

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A study of a low pressure ratio vapor injection scroll compressor for electric vehicles under low ambient conditions

International Journal of Refrigeration ◽

10.1016/j.ijrefrig.2021.08.022 ◽

2021 ◽

Author(s):

Xinxin Zhang ◽

Lin Su ◽

Kang Li

Keyword(s):

Electric Vehicles ◽

Pressure Ratio ◽

Low Pressure ◽

Ambient Conditions ◽

Scroll Compressor ◽

Vapor Injection

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Development of a Novel Two-Stage Heat Pump Clothes Dryer

Volume 6A: Energy ◽

10.1115/imece2014-36048 ◽

2014 ◽

Cited By ~ 2

Author(s):

Tao Cao ◽

Jiazhen Ling ◽

Yunho Hwang ◽

Reinhard Radermacher

Keyword(s):

Heat Exchanger ◽

Heat Pump ◽

Energy Savings ◽

Design Tool ◽

Department Of Energy ◽

Two Stage ◽

Heat Exchanger Design ◽

Clothes Dryer ◽

Vapor Injection ◽

Injection Cycle

An energy efficient two-stage heat pump clothes dryer (HPCD) was successfully developed. This new dryer utilizes three advanced technologies: vapor injection cycle, compact heat exchanger and brushless direct current (BLDC) fan motor. An in-house heat exchanger design tool – CoilDesigner was utilized to design and optimize the evaporator and condenser in the vapor injection cycle. One electric clothes dryer (CD) from U.S. market was selected as the baseline product, and one hybrid HPCD from European market was selected as the best state-of-the-art commercial product in terms of energy efficiency. These two commercial products and the constructed two-stage HPCD prototype were tested according to the Department of Energy (DOE) dryer test standards. Experimental evaluation revealed that the two-stage HPCD achieved 59% energy savings and improved energy factor (EF) by 143% as compared to the electric dryer. It also achieved 25% energy savings and improved EF by 33% as compared to the hybrid HPCD. This implied that the two-stage HPCD could save energy up to 42 TW·h annually if this technology is fully deployed to replace all U.S. electric CDs. Cost analysis indicates that the payback period of the two-stage HPCD is only 2.2 years as compared to the electric dryer with bottom cabinet. Therefore, the two-stage HPCD is an economically competitive greener option.

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