Thermosiphon Beams, Intelligent Air Distribution System

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Technology Category:
Technology Supplier:
Air T&D Pte Ltd
Originated From:
Suitability in Existing Building/New Development:
New Development
Suitability Climate Zones
Last Update Date
04/30/2019 16:50:02
Technology Keywords
ACMV, Thermosiphon Beams, Intelligent Air Distribution System, Control & Optimization System, Energy Efficiency, Indoor Environment Quality
Technology Description

This type of ACMV system consists of air treatment unit, air distribution system, air terminal unit and control system. Differentiate from existing ones are that it can achieve truly independent control of indoor temperature, humidity and ventilation (varying one parameter will not affecting others), so that both lowest energy cost and good indoor environment quality can be guaranteed.

Air treatment unit: three kinds of air treatment units are developed to satisfy different air treatment requirements. Liquid Desiccant Air Conditioning System (LDACS) (patented) which can energy efficiently dry the air to very low humidity ratio; Dual-Cycle Air Dehumidification System (DCACS) which is energy efficient, easy to use and can suit most building applications; and Energy Recovery Ventilator (ERV) which recover waste energy from exhaust air with efficiency of over 70%. These systems can be used to treat the ventilation air for dedicated outdoor air systems and can achieve 20% to 40% energy savings when applied to residential and commercial building ACMV systems.

Intelligent air distribution system: a low cost and easy-to-implement Intelligent Air Distribution System (IADS) for dynamic control of building ventilation was developed. The system consists of Indoor Air Quality Sensors, Indoor Controller, Smart Damper and Direct Digital Control System. The Direct Digital Control System receives data from the indoor controllers, Smart Dampers, and fan to build and update the mathematical model for the air duct network. The intelligent adaptive optimization algorithm then computes the required damper positions and fan speed to achieve optimum working conditions in terms of the good IEQ and minimum energy consumption.

Air terminal units: the quiet and energy efficient terminal units are designed based on four major air physical phenomenon: entrainment, thermosiphon, displacement and coanda effects. Our products include Passive Chilled Beams (PCB), Active Chilled Beams (PCB), Dual-Mode Passive Thermosiphon Beams (DMTB) and Tri-Mode Thermosiphon Beams (TMTB). Depending on the application, the combination use of these terminal units provide the best solution in terms of energy, cost and comfort.

Control system: an intelligent building management system (Building STAR) that offers functions of Energy Analytic, Modelling, Control Loop Auto-tuning, System Optimization and Fault Detection and Diagnostics.  In BSTAR, disparate building sub-systems can be integrated using a shared network such that they can all be controlled by a centralized common user interface. All information resources of each sub-system can be shared in the platform to optimize building management functions and maximize building performance and efficiency. Reliable and efficient application system with comprehensive management functions can be flexible designed for different scale of buildings, nature of businesses and style of facility management.

The operating principle of the system is as follows:

1) Chiller plant generate 10 C -12 C degree chilled water and supplied to both terminal units and air treatment units

2) The air treatment units used as Dedicated Outdoor Air system (DOAS) handle all the space latent loads and part of sensible loads

3) The treated ventilation air is supplied to different zone through Intelligent Air Distribution System (IADS) according to the space need

4) The Thermosiphon Beam (TB) terminal units provide the required sensible cooling with best Indoor Environment Quality (IEQ).

5) The Intelligent Energy Management System (BSTAR) coordinate the performance of each element so that the system performance can be optimized at part load conditions

Estimated First Cost
400.00 S$/sqm
Estimated Maintenance & Operation Cost
10.00 S$/sqm/year
Estimated Life Time
20 years
Estimated Lead Time
1 month
Technology Features
Technology Advantages

Energy Efficient

1) 10 C -12 C degree chilled water supply is 3 C -5 C higher compared with the current practice (7 C). Since every degree increase of chilled water supply temperature resulting 5% of COP improvement, this will increase chiller COP by 15% - 25%;

2) Combined Dedicated Outdoor Air System (DOAS) for air treatment and Intelligent Air Distribution System (IADS) reduce ventilation air reduced by 20-70%, resulting 10-40% energy saving in treating and distributing the air;

3) Delivering chilled water direct to the air water terminals inside the space instead of centralized air treatment in AHUs reduces both fan power and energy losses through the duct works. This will resulting 5-10% higher efficiency;

4) Through modelling, control and optimization, the intelligent energy management system-BSTAR can coordinate the performance of each function block at part load condition, this will further generate 10-15% energy saving.

Better IEQ

·     1) With air treatment unit to handle all the space latent load, duct work and terminal units are working under dry operation that eliminate bacteria growth and remove airborne microorganisms;

·     2) The displacement ventilation offers better air diffusion performance, which leads to lower airflow velocities, reduced drafts and more effective in remove airborne microorganisms etc.;

·     3) The IADS control the ventilation rate according to the indoor air quality requirement, there is no over/under ventilation;

·     4) There is no centralized recirculation air for different zones, so there should be no cross-contamination between spaces served by the system;

·     5) The system typically operates with sound levels below 30 NC.

Other benefits

1) For new buildings, one floor area can be created for every five floor of construction. This means the cost reduction, or 25% floor space increment;

2) Reduction in sizes and capacities of the air treatment, and air distribution and chiller, results big savings in equipment, operation and maintenance costs.

Technology Limitation

The proposed ACMV system operates in cooling mode. In areas that need heating, the system design and control strategy need to be adjusted.

Cost and Benefit Analysis

Assume an office building in Singapore with the areas of conditioned space of 2400m2 which is divided into 5 zones, the temperature and humidity set-points are 25°C and 60% RH, respectively, and operate from 8am to 10pm every day. Each zone is designed for occupants, computers and other electrical appliances.

Internal load: The summary of design information for the space is listed in Table 1.

Table 1 Summary of design information

Total Latent Load


Total Sensible Load


Total Load


Ventilation: The ventilation requirement for each zone is calculated to meet ventilation codes. For example, using ASHRAE Standard 62-2010 to determine the minimum fresh air flow rate for a typical office space:

Let the occupancy rate of 5m2/person, the ventilation loads for the Zones are

                           Total:    1920L/s.

For the conventional VAV system:

The energy consumptions for the VAV system with cooling based DOAS are:

              DOAS Chillers:    65.24kW

              Fans:                  9.19kW

 Pumps:               2.04kW

              Total:                  76.47kW

For the proposed ACMV system:

The energy consumptions for the proposed ACMV system are:

              Chiller:               35.93kW

              Fans:                  2.933kW

 Pumps:               1.26kW

              Total:                  40.12kW

Compare the two systems, the system bases IERV and hybrid air terminals is much more energy efficient. The saving is