This thesis research aims to develop an improved, efficient, low-capacity heat engine, running on an Organic Rankine Cycle (ORC) to generate power. The ORC is driven by low or moderate temperature heat sources, such as; renewable energy in the form of a hot gas derived from biomass/biogas/biofuel combustion streams, waste heat recovery, process heat recovery, etc. The ORC is more suitable and flexible than a conventional steam Rankine cycle, especially when it is applied to low power range. In this research, an extended surface heat exchanger is used to boil the pressurised working fluid, R134a, using a hot air as heat source. The expander used is a scroll type, coupled to a generator, which is able to produce maximum 1.6 kW output. Experimental data of the heat engine are measured under different operating conditions and utilized in the analysis and comparisons. Power generation under various conditions is investigated in order to determine the optimum performance parameters for the heat engine. The isentropic efficiency of the expander is found to be over 40% and reaches 80% for the improved expansion conditions. For the boiler, it is determined that the overall heat transfer coefficient multiplied with the heat transfer area is around 150 W/K. The energy efficiency of the experimental ORC is around 3% for hot air as the low temperature heat source at about 105oC where exergy efficiency reaches 22%, respectively. / UOIT

4th generation district heating (4GDH) and varying the indoor temperature to store heat are both important concepts that can make it easier to implement more renewable energy and reduce costs of heating. This study looks at these concepts from a customer perspective using one building and looking at how energy can be stored and the performance of 4GDH. Low temperature heat sources from industry, supermarkets, and datacentres are used in combination with heat from a combined heat and power plant to get the required heating. A heat pump has also been modelled as a part of the 4GDH structure. In addition to looking at heat storage in 4GDH a scenario with direct electric heating has also been evaluated. In conclusion 4GDH has lower operating costs than 3rd generation district heating, but it is not worth varying the indoor temperature to store energy when using 4GDH. It is, however, profitable to vary indoor temperature if direct electric heating is used.