Studies on integration of energy supply and utilization systems are reported. Purely thermal systems (heating and cooling and heating-only systems), thermomechanical systems (combined heat and power), and purely mechanical systems (integrated energy delivery systems) are discussed. It is concluded that there is a broad scope for optimization of integrated supply systems.Keywords heating and cooling systems, integrated supply systems, purely heating systems, solar heaters, source integration, task integration An important way of increasing utilization, energetic, and exergetic efficiencies of energy conversion and utilization systems is through integration. Systems are integrated through sources or tasks, spatially or timewise to reduce their overall energy consumption, enhance the security of energy supply, and reduce capital and running costs of equipment (Siddhartha Bhatt, 1985).The efficacy of integration can be quantified with the use of the availability function A:where U is the internal energy, p the pressure, V the volume, T the temperature, S the entropy, and E the energy. The availability of source-device units can be represented asThe availability of tasks can be represented as For "p" tasks put together, it is possible to have a combination of sources and devices where the availability is minimum (A,-,i,).Matching of energy sources, tasks, and devices can be accomplished in a number of ways (Siddhartha Bhatt, 1984), such as 1. common energy mode (all sources are converted to one common form of energy such as electrical energy),Siddhartha Bhatt et al.2. one energy mode (one source provides energy for all tasks without intermediate conversion into a common energy form), 3. multienergy mode (tasks are performed by a mix of sources that match it), and 4. complex energy mode (combines the multisource mode of the common energy mode and multienergy mode). This is the most general form of the energy conversion and utilization mode.The efficiency of matching between a source device and a task is given byThe multienergy mode is the most efficiently matched from both energetic and exergetic considerations. The minimum input availability of a source-device system (As-mi,) can be used to determine the efficiency of integration as follows:When 77 + 1.0, systems are said to be well integrated. Common energy modes and one energy mode are poor examples of system integration and tend to give a low value of efficiency of integration. Energy cascading (waste heat recovery and bottoming cycles), exergetic cascading (power generation using topping cycles), and timewise integration tend to increase the efficiency of integration. Some of the rules of cascaded integration involving mechanical and thermal energy components (Linnhoff, 1989) are the following:1. Heat transfer across the pinch point must be minimum.
