The Experts below are selected from a list of 180 Experts worldwide ranked by ideXlab platform

Shengwei Wang - One of the best experts on this subject based on the ideXlab platform.

  • Test and evaluation of energy saving potentials in a complex building central Chilling System using genetic algorithm
    Building Services Engineering Research and Technology, 2010
    Co-Authors: Shengwei Wang
    Abstract:

    This article presents the test and evaluation of energy saving potentials of complex building central Chilling Systems using genetic algorithm (GA). The evaluation was conducted based on a simulated virtual System representing the actual complex central Chilling System in a super high-rise building in Hong Kong. GA was used as the optimisation tool to search for globally optimal control settings. The simulated virtual System was used as the test platform and acted as the performance predictor in estimating the overall System performance and responses to the changes of control settings. The test results show that about 4.54—5.06% daily energy in the System studied can be saved by using optimal control settings, as compared to that using the conventional control settings. The results also show that the evaluation process by using the simulated virtual System and the GA optimiser is time costly due to strong dynamic effects of the simulated virtual System and the optimisation principle of GA.Practical applic...

  • online performance evaluation of alternative control strategies for building cooling water Systems prior to in situ implementation
    Applied Energy, 2009
    Co-Authors: Shengwei Wang, Fu Xiao
    Abstract:

    This paper presents the online test and evaluation of the performance of five practical control strategies (fixed set-point control method, fixed approach control method, two near optimal strategies and one optimal strategy) for building cooling water Systems to identify the best strategy for future field validation. All of these strategies were tested and evaluated in a simulated virtual environment similar to the situation when they are actually implemented in practice. A virtual building System representing the real building and its central Chilling System was developed and used to test the operational performance of the System controlled by different strategies. The packages of each control strategy are separately computed by the application program of Matlab, as the control optimizers to identify the necessary control settings for the given condition based on the collected operation data. The data exchanger between the virtual building System and the control optimizer was managed by a software platform through a communication interface. The results showed that the optimal control strategy is more energy efficient and cost effective than the other strategies, and its computational cost is manageable and can satisfy the requirements of practical applications. This strategy is being implemented in a super high-rise building for field validation.

  • Online optimal control of the central Chilling System in a super high-rise commercial building
    2008
    Co-Authors: Shengwei Wang
    Abstract:

    ABSTRACT This paper presents the online optimal control strategies of the central Chilling System in a super high-rise building in Hong Kong. The work presented aims at developing a package of optimal control strategies and evaluating their energy saving potentials and finally implementing these strategies in the building to enhance its energy efficiency. Based on testing the effects of interactions within the cooling water System and chilled water System on the System operation performance, the optimal control strategies for the cooling water System and variable speed pumps with different installations in the secondary chilled water System are developed. These strategies are tested and validated in a virtual environment representing the real building System and its central Chilling System prior to site implementation. The implementation issues the online control strategies for practical application are also addressed. 1. INTRODUCTION The growing concern on energy or cost efficiency has motivated society and building professionals to pay more attention on the overall System optimal control and provides incentives to develop the more extensive and robust control strategies for HVAC Systems. Supervisory and optimal control, which addresses energy or cost efficient control of HVAC Systems while providing desired indoor comfort and healthy environment under dynamic working conditions, is one of the main achievable approaches to minimize building energy consumption/operating costs and provide robust control performance. Buildings nowadays are mostly equipped with comprehensive building automation Systems (BASs) and building energy management and control Systems (EMCSs) that allow the possibility of enhancing and optimizing the operation and control of HVAC Systems. Over the last two decades or so, efforts have been made to develop supervisory and optimal control strategies for building HVAC Systems thanks to the growing scale of BAS integration and the convenience of collecting a large amount of online operation data by the application of BASs. These efforts have resulted in many research papers and technical articles that specifically address the HVAC optimal control and operation available in literature (Wang and Jin, 2000; Sun and Reddy, 2005; etc.). In cooling water Systems, cooling towers are usually used for heat rejection purposes and the fans are equipped with variable frequency drivers (VFD) to control the condenser water supply temperature at its set-point intended. There are many existing control strategies for cooling towers. The simple strategy is to maintain a constant condenser water supply temperature set-point (i.e., fixed set-point) or to maintain a constant difference between the condenser water supply temperature set-point and the ambient air wet-bulb temperature (i.e., fixed approach) by varying the air flow rate through the cooling towers (Crowther and Furlong, 2004). Several near optimal control strategies have been also proposed to determine a near optimal condenser water supply temperature set-point, and then utilize this temperature set-point to approximately control the operation of the cooling towers (Braun and Diderrich, 1990; Sun and Reddy, 2005; etc.). These strategies are simple enough and easy to implement in practice. However, these strategies cannot provide the true optimal settings, which might provide the settings significantly different from the optimal values, and a significant amount of energy might still be wasted. The energy costs of variable speed pumps form an important part of the total energy consumption of buildings. Aiming at enhancing the operating efficiency of pumps and prolonging their service life, a number of researchers and experts in the HVAC field have devoted considerable efforts on energy efficient control and operation of variable speed pumps in HVAC Systems in the course of past years (Burke, 1995; Bahnfleth and Peyer, 2001; Rishel,

  • Sensor validation and reconstruction for building central Chilling Systems based on principal component analysis
    Energy Conversion and Management, 2004
    Co-Authors: Shengwei Wang, Youming Chen
    Abstract:

    This paper presents an automatic and online FDD (fault detection and diagnose) and sensor reconstruction scheme that can be used in a building energy management and control System to detect and diagnose sensor faults and reconstruct faulty sensors in building central Chilling Systems. The scheme is based on principal component analysis to build a model that captures the correlation among the flow meters and temperature sensors installed in the Chilling Systems. The model is employed to reconstruct an assumed faulty sensor. The square prediction error based on the model and the sensor validity index based on the construction are employed, respectively, to detect the sensor fault and identify the faulty sensor. An existing building central Chilling System is simulated to test and validate the developed scheme online. Four types of sensor faults are introduced, respectively, during the simulation to validate the sensor FDD and sensor reconstruction scheme.

  • Online adaptive control for optimizing variable-speed pumps of indirect water-cooled Chilling Systems
    Applied Thermal Engineering, 2001
    Co-Authors: Shengwei Wang, John Burnett
    Abstract:

    An online control strategy is developed to optimize the speed of variable speed condenser cooling water pumps by resetting their pressure set-point, which includes an adaptive and a derivative control strategy. Optimal control is achieved by adjusting the pressure set-point according to the estimated derivative of the total power with respect to pressure. The adaptive strategy identifies the changes of the System parameters essential for the control strategy and updates the control accordingly. The control strategies, the implementation and evaluation of the control strategies on an indirect seawater-cooled Chilling System with multiple pumps and chillers are presented.

C James - One of the best experts on this subject based on the ideXlab platform.

  • decontamination of poultry carcasses using steam or hot water in combination with rapid cooling Chilling or freezing of carcass surfaces
    International Journal of Food Microbiology, 2007
    Co-Authors: C James, S J James, Neil Hannay, G L Purnell, Catia S Barbedopinto, Hilmi Yaman, Marlene Araujo, Luisa M Gonzalez, Javier Fernandez Calvo, M Howell
    Abstract:

    The effects of the application of steam at atmospheric pressure for times up to 20 s on the numbers of inoculated Campylobacter jejuni and Escherichia coli on whole chicken carcasses were investigated in a pilot steam cabinet. Steam treatments reduced the numbers of C. jejuni AR6 by ca. 1.8, 2.6 and 3.3 log(10) cfu cm(-2) in 10, 12 and 20 s, respectively. Corresponding reductions in numbers of E. coli K12 were 1.7, 2.3 and 2.8 log(10) cfu cm(-2). However, such treatments caused the skin to shrink and change colour. The optimum treatment for maximum reductions of C. jejuni and E. coli, least skin shrinkage and change of colour was concluded to be <12 s. Further work was carried out to determine whether a modified air Chilling System in combination with steam or hot water decontamination treatments could be used to reduce numbers of pathogens, particularly campylobacters, on the surface of poultry carcasses. Whole chicken carcasses inoculated with C. jejuni and E. coli were either not treated, treated with steam at atmospheric pressure for up to 10 s or treated with hot water at 80 degrees C for up to 20 s, then either chilled by crust freezing, chilled at 0 degrees C, or chilled at 15 degrees C, in a pilot Chilling chamber. The optimum combination was treatment with water at 80 degrees C for 20 s followed by crust freezing, which reduced the numbers of C. jejuni and E. coli by ca. 2.9 and 3.2 log(10) cfu cm(-2), respectively, without extensive degradation of carcass appearance.

  • the primary Chilling of poultry carcasses a review
    International Journal of Refrigeration-revue Internationale Du Froid, 2006
    Co-Authors: C James, C Vincent, T I De Andrade Lima, Stephen James
    Abstract:

    Abstract This paper reviews the published scientific studies that have been carried out on the Chilling of poultry carcasses. The prime purpose of Chilling is to limit the growth of both pathogenic and food spoilage microorganisms. There are a wide range of publications that show that, in general, the numbers of both types of microorganism, on the surface of poultry carcasses, is reduced during the Chilling process. Immersion or spin Chilling is not used in the production of ‘fresh’ chilled poultry in Europe, ‘dry’ air Chilling being the preferred Chilling method. Many people believe that there is some clear microbiologically based reason behind the selection of air Chilling. However, the published data do not appear to support this belief, and if anything point to a microbial advantage of immersion Systems. The rate of Chilling has some influence on the taste, texture and appearance of poultry meat. Very rapid Chilling can result in tougher chicken meat, while very slow Chilling can produce pale soft exudative (PSE) muscle. However, in both cases the effect is not as marked as with red meat. No comprehensive published data has been found on the effect of a range of Chilling Systems, Chilling conditions, carcass weight and shape on the rate of Chilling, weight loss and heat loss. Without such data it is impossible to optimise the design of a poultry Chilling System.

  • The primary Chilling of poultry carcasses—a review
    International Journal of Refrigeration, 2006
    Co-Authors: C James, C Vincent, T I De Andrade Lima, Stephen J. James
    Abstract:

    Abstract This paper reviews the published scientific studies that have been carried out on the Chilling of poultry carcasses. The prime purpose of Chilling is to limit the growth of both pathogenic and food spoilage microorganisms. There are a wide range of publications that show that, in general, the numbers of both types of microorganism, on the surface of poultry carcasses, is reduced during the Chilling process. Immersion or spin Chilling is not used in the production of ‘fresh’ chilled poultry in Europe, ‘dry’ air Chilling being the preferred Chilling method. Many people believe that there is some clear microbiologically based reason behind the selection of air Chilling. However, the published data do not appear to support this belief, and if anything point to a microbial advantage of immersion Systems. The rate of Chilling has some influence on the taste, texture and appearance of poultry meat. Very rapid Chilling can result in tougher chicken meat, while very slow Chilling can produce pale soft exudative (PSE) muscle. However, in both cases the effect is not as marked as with red meat. No comprehensive published data has been found on the effect of a range of Chilling Systems, Chilling conditions, carcass weight and shape on the rate of Chilling, weight loss and heat loss. Without such data it is impossible to optimise the design of a poultry Chilling System.

Francis Butler - One of the best experts on this subject based on the ideXlab platform.

  • impact of a novel spray Chilling System on surface microflora water activity and weight loss during beef carcass Chilling
    Food Microbiology, 2006
    Co-Authors: K J Kinsella, J J Sheridan, T A Rowe, Francis Butler, A Delgado, A Quisperamirez, I S Blair, D A Mcdowell
    Abstract:

    Commercially slaughtered and dressed beef carcass sides (n=30) were followed through a standard commercial chill unit fitted with a new “Jasca” air humidification System adjusted to provide intermittent water spraying of carcass sides (spray cycle 2 min on, 1 min off) for 15 h. Immediately after dressing, and after 24 h in the chill unit, the surface water activity, and the weight of each side was measured, and 5 cm2 samples were recovered from four locations, i.e. rump, flank, brisket and neck on the surface of each side. These samples, and similar samples from control sides (n=30) processed in a standard commercial chill unit, were subjected to microbiological examination by direct and resuscitation counts on plate count agar (PCA), MacConkey agar (MAC) and violet red bile glucose agar (VRBGA). No significant differences were observed between bacterial numbers on test and control samples on each of the above agars, at each sample point/occasion. Comparison of direct and resuscitation counts suggested the presence of substantial numbers of injured cells, at both stages (pre- and post-chill), on test and control sides. After 24 h in chill units, test sides exhibited an average weight loss of 1.36% (±0.36%), which is significantly less (P<0.001) than the average weight loss (1.55%±0.24%) from control sides. These results suggest that the Jasca spray-Chilling System can limit carcass shrinkage (on average by 0.19%) without significantly increasing the surface populations of selected bacterial groups.

  • Impact of a novel spray-Chilling System on surface microflora, water activity and weight loss during beef carcass Chilling
    Food microbiology, 2005
    Co-Authors: K J Kinsella, T A Rowe, Francis Butler, A Delgado, I S Blair, James J. Sheridan, A. Quispe-ramirez, D A Mcdowell
    Abstract:

    Commercially slaughtered and dressed beef carcass sides (n=30) were followed through a standard commercial chill unit fitted with a new “Jasca” air humidification System adjusted to provide intermittent water spraying of carcass sides (spray cycle 2 min on, 1 min off) for 15 h. Immediately after dressing, and after 24 h in the chill unit, the surface water activity, and the weight of each side was measured, and 5 cm2 samples were recovered from four locations, i.e. rump, flank, brisket and neck on the surface of each side. These samples, and similar samples from control sides (n=30) processed in a standard commercial chill unit, were subjected to microbiological examination by direct and resuscitation counts on plate count agar (PCA), MacConkey agar (MAC) and violet red bile glucose agar (VRBGA). No significant differences were observed between bacterial numbers on test and control samples on each of the above agars, at each sample point/occasion. Comparison of direct and resuscitation counts suggested the presence of substantial numbers of injured cells, at both stages (pre- and post-chill), on test and control sides. After 24 h in chill units, test sides exhibited an average weight loss of 1.36% (±0.36%), which is significantly less (P

  • Optimising a rapid Chilling System for lamb carcasses
    Journal of Food Engineering, 2002
    Co-Authors: B. Mcgeehin, James J. Sheridan, Francis Butler
    Abstract:

    Abstract 12 rapid Chilling treatments using different air speeds, temperatures and durations of the initial rapid Chilling stage were tested to optimise rapid Chilling of lamb in terms of weight loss and tenderness. Results showed that there was a linear increase in weight loss with chill temperature. Shear force values increased with chill duration. There was a linear increase in day 5 tenderness scores with chill temperature. Overall the results showed that rapid Chilling for 2.5 h using air speed of 0.5 m s −1 and a temperature of −20°C gave the best results overall in terms of reducing evaporative weight losses and maintaining tenderness.

D A Mcdowell - One of the best experts on this subject based on the ideXlab platform.

  • impact of a novel spray Chilling System on surface microflora water activity and weight loss during beef carcass Chilling
    Food Microbiology, 2006
    Co-Authors: K J Kinsella, J J Sheridan, T A Rowe, Francis Butler, A Delgado, A Quisperamirez, I S Blair, D A Mcdowell
    Abstract:

    Commercially slaughtered and dressed beef carcass sides (n=30) were followed through a standard commercial chill unit fitted with a new “Jasca” air humidification System adjusted to provide intermittent water spraying of carcass sides (spray cycle 2 min on, 1 min off) for 15 h. Immediately after dressing, and after 24 h in the chill unit, the surface water activity, and the weight of each side was measured, and 5 cm2 samples were recovered from four locations, i.e. rump, flank, brisket and neck on the surface of each side. These samples, and similar samples from control sides (n=30) processed in a standard commercial chill unit, were subjected to microbiological examination by direct and resuscitation counts on plate count agar (PCA), MacConkey agar (MAC) and violet red bile glucose agar (VRBGA). No significant differences were observed between bacterial numbers on test and control samples on each of the above agars, at each sample point/occasion. Comparison of direct and resuscitation counts suggested the presence of substantial numbers of injured cells, at both stages (pre- and post-chill), on test and control sides. After 24 h in chill units, test sides exhibited an average weight loss of 1.36% (±0.36%), which is significantly less (P<0.001) than the average weight loss (1.55%±0.24%) from control sides. These results suggest that the Jasca spray-Chilling System can limit carcass shrinkage (on average by 0.19%) without significantly increasing the surface populations of selected bacterial groups.

  • Impact of a novel spray-Chilling System on surface microflora, water activity and weight loss during beef carcass Chilling
    Food microbiology, 2005
    Co-Authors: K J Kinsella, T A Rowe, Francis Butler, A Delgado, I S Blair, James J. Sheridan, A. Quispe-ramirez, D A Mcdowell
    Abstract:

    Commercially slaughtered and dressed beef carcass sides (n=30) were followed through a standard commercial chill unit fitted with a new “Jasca” air humidification System adjusted to provide intermittent water spraying of carcass sides (spray cycle 2 min on, 1 min off) for 15 h. Immediately after dressing, and after 24 h in the chill unit, the surface water activity, and the weight of each side was measured, and 5 cm2 samples were recovered from four locations, i.e. rump, flank, brisket and neck on the surface of each side. These samples, and similar samples from control sides (n=30) processed in a standard commercial chill unit, were subjected to microbiological examination by direct and resuscitation counts on plate count agar (PCA), MacConkey agar (MAC) and violet red bile glucose agar (VRBGA). No significant differences were observed between bacterial numbers on test and control samples on each of the above agars, at each sample point/occasion. Comparison of direct and resuscitation counts suggested the presence of substantial numbers of injured cells, at both stages (pre- and post-chill), on test and control sides. After 24 h in chill units, test sides exhibited an average weight loss of 1.36% (±0.36%), which is significantly less (P

Stephen J. James - One of the best experts on this subject based on the ideXlab platform.

  • The primary Chilling of poultry carcasses—a review
    International Journal of Refrigeration, 2006
    Co-Authors: C James, C Vincent, T I De Andrade Lima, Stephen J. James
    Abstract:

    Abstract This paper reviews the published scientific studies that have been carried out on the Chilling of poultry carcasses. The prime purpose of Chilling is to limit the growth of both pathogenic and food spoilage microorganisms. There are a wide range of publications that show that, in general, the numbers of both types of microorganism, on the surface of poultry carcasses, is reduced during the Chilling process. Immersion or spin Chilling is not used in the production of ‘fresh’ chilled poultry in Europe, ‘dry’ air Chilling being the preferred Chilling method. Many people believe that there is some clear microbiologically based reason behind the selection of air Chilling. However, the published data do not appear to support this belief, and if anything point to a microbial advantage of immersion Systems. The rate of Chilling has some influence on the taste, texture and appearance of poultry meat. Very rapid Chilling can result in tougher chicken meat, while very slow Chilling can produce pale soft exudative (PSE) muscle. However, in both cases the effect is not as marked as with red meat. No comprehensive published data has been found on the effect of a range of Chilling Systems, Chilling conditions, carcass weight and shape on the rate of Chilling, weight loss and heat loss. Without such data it is impossible to optimise the design of a poultry Chilling System.