Experimental investigation on the steady-state performance and piston stroke length control of a variable displacement wobble plate compressor

2005 ◽  
Vol 219 (2) ◽  
pp. 271-281 ◽  
Author(s):  
Changqing Tian ◽  
Chunpeng Dou ◽  
Xianting Li ◽  
Yunfei Liao
Keyword(s):  
Experimental Investigation ◽  
Steady State ◽  
Test Data ◽  
Air Conditioning ◽  
Volumetric Efficiency ◽  
Stroke Length ◽  
Variable Displacement ◽  
Rotary Speed ◽  
Piston Stroke ◽  
Steady State Performance

The aim of this paper is to find out the steady-state performance and piston-stroke-length control behaviour of a variable displacement wobble-plate compressor for an automotive air-conditioning system by experimental investigation. First, a new method and device to measure the piston stroke length of the variable displacement compressor has been developed, with which the test bench for the variable displacement compressor has been set up. Second, the steady-state performance of the variable displacement compressor, such as the relative volumetric efficiency and the relative isentropic efficiency at partial piston stroke length, has been obtained. The influence of the work condition and compressor rotary speed on the relative volumetric efficiency can be neglected according to the test data. Finally, the critical wobble-plate case pressure is proposed in this paper to judge whether the piston stroke length will change or not. The critical wobble-plate case pressure when the piston stroke length decreases is greater than that when the piston stroke length increases, which is less influenced by the piston stroke length itself from the test data. The higher the compressor discharge pressure or rotary speed, the greater the critical wobble-plate case pressure. The piston stroke length can be adjusted automatically along with the air-conditioning load when the compressor rotary speed or air conditioning load changes.

Steady-State Performance of a Prototype (200 cfm) Liquid-to-Air Membrane Energy Exchanger (LAMEE) Under Summer and Winter Test Conditions

2013 ◽  
Author(s):  
Davood Ghadiri Moghaddam ◽  
Gazi Mahmood ◽  
Gaoming Ge ◽  
John Bolster ◽  
Robert W. Besant ◽  
...  
Keyword(s):  
Steady State ◽  
Salt Solution ◽  
Air Conditioning ◽  
Winter Conditions ◽  
Test Conditions ◽  
Membrane Energy ◽  
Air Conditioning Systems ◽  
New Generation ◽  
Heat And Moisture ◽  
Steady State Performance

Liquid-to-air membrane energy exchangers (LAMEEs) are a new generation of energy exchangers in air-conditioning systems to transfer both heat and moisture. In this paper, the performance of a 200 cfm LAMEE is numerically and experimentally investigated under summer and winter test conditions when Lithium Chloride (LiCl) is used as a salt solution in the exchanger. The results show that the LAMEE has almost the same total effectiveness at summer and winter conditions, but the latent effectiveness of the LAMEE is higher at the summer conditions. Also, the agreement between the experimental and numerical results is acceptable for all the tests, and they are within their uncertainty ranges except for the latent effectiveness of the LAMEE tested under winter test conditions.

Experimental Testing of a Variable Displacement Pump/Motor That Uses a Hydro-Mechanically Timed Digital Valving Mechanism to Achieve Partial-Stroke Piston Pressurization (PSPP)

2019 ◽  
Author(s):  
Alissa Montzka ◽  
Nathan Epstein ◽  
Michael Rannow ◽  
Thomas R. Chase ◽  
Perry Y. Li
Keyword(s):  
High Pressure ◽  
Experimental Testing ◽  
Power Level ◽  
Mechanical Valve ◽  
Hydraulic Pump ◽  
Stroke Length ◽  
Displacement Pump ◽  
Variable Displacement ◽  
Piston Stroke ◽  
Axial Piston

Abstract This work describes an efficient means to adjust the power level of an axial piston hydraulic pump/motor. Conventionally, the displacement of a piston pump is varied by changing the stroke length of each piston. Since the losses do not decrease proportionally to the displacement, the efficiency is low at low displacements. Here, with partial-stroke piston pressurization (PSPP), displacement is varied by changing the portion of the piston stroke over which the piston is subjected to high pressure. Since leakage and friction losses drop as the displacement is decreased, higher efficiency is achieved at low displacements with PSPP. While other systems have implemented PSPP with electric or cam-actuated valves, the pump described in this paper is unique in implementing PSPP by way of a simple, robust hydro-mechanical valve system. Experimental testing of a prototype PSPP pump/motor shows that the full load efficiency is maintained even at low displacements.

Theoretical and experimental studies of the steady-state performance of a primary and secondary-controlled closed-circuit hydrostatic drive

2019 ◽  
Vol 233 (5) ◽  
pp. 1024-1035
Author(s):  
Ajit Kumar Pandey ◽  
Alok Vardhan ◽  
K Dasgupta
Keyword(s):  
Steady State ◽  
System Modeling ◽  
Experimental Studies ◽  
Simulation Method ◽  
Closed Circuit ◽  
Displacement Pump ◽  
Torque Loss ◽  
Variable Displacement ◽  
Graph Simulation ◽  
Steady State Performance

In this article, performance of a closed-circuit hydrostatic drive in primary and secondary mode of operations has been studied through theory and experiment. This drive consists of a variable displacement pump that supplies pressurized fluid to a variable displacement hydro-motor of bent axis design. Bond graph simulation method is adopted for system modeling. In the model, the losses of the drive are accounted by suitable resistive elements, and their characteristics are identified through experiments. The predicted drive’s performances are studied with respect to the overall efficiency, torque loss (%), and slip at different torque levels which are also validated experimentally. The investigation made in the article identifies the efficient zone of operation of the drive which will be useful to the practicing engineers to select such a drive used in heavy constructional equipment. From the steady-state performance of the pump and the motor, their critical control parameters are identified. The studies may be useful for the design of the suitable control strategy to obtain the optimum performance of the drives.

Steady-state performance investigation of closed-circuit hydrostatic drive using variable displacement pump and variable displacement motor

2020 ◽  
pp. 095440892095366
Author(s):  
Vinay Partap Singh ◽  
Ajit Kumar Pandey ◽  
Kabir Dasgupta
Keyword(s):  
Steady State ◽  
Closed Circuit ◽  
Control Parameters ◽  
Prime Mover ◽  
Load Torque ◽  
Wide Range ◽  
Displacement Pump ◽  
Variable Displacement ◽  
Overall Performance ◽  
Steady State Performance

This article investigates the steady-state performance of a closed-circuit hydrostatic (HST) drive using a variable displacement pump and a variable displacement motor where the speed of the drive is varied by controlling pump or motor. The drive is operated over a wide range of load torque and speed in two modes of operation: the pump controlled mode and the motor controlled mode. The efficiencies of the pump, motor, and the prime mover driving the pump are taken into account to analyze the overall performance of the drive. In this respect, considering various flow and torque losses of the HST drive components, the equations representing efficiencies of the drive are identified by comparing with the experimental data. The simulation is carried out using MATLAB. The results of the study may be useful to identify the control parameters of the drive to operate it at a reasonable efficiency zone.

Steady-state performance investigation of hydrostatic summation drive using bent-axis hydraulic motor

2014 ◽  
Vol 229 (17) ◽  
pp. 3234-3251 ◽  
Author(s):  
N Kumar ◽  
K Dasgupta
Keyword(s):  
Steady State ◽  
Performance Studies ◽  
State Variables ◽  
Hydraulic Motor ◽  
Displacement Pump ◽  
Torque Loss ◽  
Variable Displacement ◽  
Loss Coefficients ◽  
Overall Efficiency ◽  
Steady State Performance

This article investigates the steady-state performance of a closed-circuit hydrostatic summation drive used in heavy earth moving machine through modelling and experiment. The proposed drive basically consists of variable displacement pump and bent-axis motor. The performance studies of the drive have been made for its two different modes of operation: using single motor and two motors. Bondgraph simulation technique is used to model the drive, where various losses are lumped into suitable resistive elements. The relationships of the losses with the state variables obtained from the model are identified through experiments. The dependencies of the loss characteristics on the load torque and the pump displacement ratio are studied. The model has been verified experimentally. The performances of the hydrostatic drives are studied at different torque levels with respect to its slip, torque-loss and overall efficiency, using the expressions describing the characteristics of the loss-coefficients. The investigation also identifies the operating range of the proposed hydrostatic drives with reasonable efficiency.

Heat and Mass Transfer in Rotary Heat Exchangers With Nonhygroscopic Rotor Materials

1977 ◽  
Vol 99 (2) ◽  
pp. 196-202 ◽  
Author(s):  
R. B. Holmberg
Keyword(s):  
Mass Transfer ◽  
Heat Conduction ◽  
Steady State ◽  
Heat Exchanger ◽  
Heat And Mass Transfer ◽  
Heat Exchangers ◽  
Air Conditioning ◽  
Absolute Humidity ◽  
Difference Type ◽  
Steady State Performance

Heat and mass transfer in rotary heat exchangers with nonhygroscopic rotor materials have been investigated. A numerical method of the finite-difference type is applied to the steady-state performance under conditions of finite rotational speed and finite longitudinal heat conduction. Temperature and absolute humidity distributions are calculated for a set of rotary heat exchanger parameters typical in air conditioning, and temperature and humidity efficiencies are evaluated for different inlet air conditions.

Quasi-steady-state performance of a heat pipe subjected to transient acceleration loadings

10.2514/3.895 ◽  
1997 ◽  
Vol 11 ◽  
pp. 306-309 ◽  
Author(s):  
Edwin H. Olmstead ◽  
Edward S. Taylor ◽  
Meng Wang ◽  
Parviz Moin ◽  
Scott K. Thomas ◽  
...  
Keyword(s):  
Steady State ◽  
Heat Pipe ◽  
Quasi Steady State ◽  
Steady State Performance
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